Add cxxstd variant to geos spack package

[victorapm]

Centralize C++ standard specification in the geos spack package.

Fixes build issues with fmt:

[  2%] Building CXX object coreComponents/common/CMakeFiles/common.dir/format/table/TableData.cpp.o
cd geos-path/build-z5tux-linux-ubuntu24.04-x86_64_v4-gcc@14.2.0-relwithdebinfo/coreComponents/common && /usr/bin/g++ -DFMT_HEADER_ONLY=1 -DH5_BUILT_AS_DYNAMIC_LIB -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -D_LARGEFILE_SOURCE -D_POSIX_C_SOURCE=200809L -Dcommon_EXPORTS -Igeos-path/build-z5tux-linux-ubuntu24.04-x86_64_v4-gcc@14.2.0-relwithdebinfo/include -Igeos-path/src/coreComponents -isystem mpich-path/install/release/include -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/chai-2025.09.1-gk6l5bpoiovwcf2sq7l6mi4luwgfjfxm/include -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/fmt-10.0.0-qyyuwcobqfdlgsootdanxk2vyje6iiyu/include -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/camp-2025.09.2-s3ucrzd2huxjlh2qggjkh4m77h6agz5q/include -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/umpire-2025.09.0-tpfn435w3jjan4ehhtz3ptybbtifv4yk/include -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/umpire-2025.09.0-tpfn435w3jjan4ehhtz3ptybbtifv4yk/include/umpire -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/raja-2025.09.1-kmrbgrn2kxgsa3dln4fk2ckq62taa3gh/include -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/caliper-2.14.0-xpa4sm663v3xubub4dgnmucgjy5fv2d4/include -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/adiak-0.4.0-slopdor4vxdl35svpnosrx47mgnoxg3f/include -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/conduit-0.9.5-3gso4lj22ejm22dy7tu5zt2n6vimgtum/include -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/conduit-0.9.5-3gso4lj22ejm22dy7tu5zt2n6vimgtum/include/conduit -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/hdf5-1.14.6-wyjb22bc4ylwcp4qzhxstvosihka6dkw/include -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/zlib-ng-2.3.2-fq4lg6maxo3dksbpx4qnktg2gbqlqj6d/include -isystem geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/pugixml-1.13-mue7aq5ibrdvpzwz3pdmcfjxiezdmdyh/include -Wall -Wextra       -Werror  -fopenmp  -Wpedantic -pedantic-errors -Wshadow -Wfloat-equal -Wcast-align -Wcast-qual  -O2 -g -DNDEBUG -std=c++17 -fPIC -fopenmp -MD -MT coreComponents/common/CMakeFiles/common.dir/format/table/TableData.cpp.o -MF CMakeFiles/common.dir/format/table/TableData.cpp.o.d -o CMakeFiles/common.dir/format/table/TableData.cpp.o -c geos-path/src/coreComponents/common/format/table/TableData.cpp
In file included from /usr/include/c++/14/list:62,
                 from geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/umpire-2025.09.0-tpfn435w3jjan4ehhtz3ptybbtifv4yk/include/umpire/ResourceManager.hpp:10,
                 from geos-path/src/coreComponents/common/BufferAllocator.hpp:26,
                 from geos-path/src/coreComponents/common/DataTypes.hpp:29,
                 from geos-path/src/coreComponents/common/Units.hpp:23,
                 from geos-path/src/coreComponents/common/format/table/TableData.hpp:23,
                 from geos-path/src/coreComponents/common/format/table/TableData.cpp:20:
In static member function ‘static _Up* std::__copy_move<_IsMove, true, std::random_access_iterator_tag>::__copy_m(_Tp*, _Tp*, _Up*) [with _Tp = unsigned int; _Up = unsigned int; bool _IsMove = false]’,
    inlined from ‘_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false; _II = unsigned int*; _OI = unsigned int*]’ at /usr/include/c++/14/bits/stl_algobase.h:521:30,
    inlined from ‘_OI std::__copy_move_a1(_II, _II, _OI) [with bool _IsMove = false; _II = unsigned int*; _OI = unsigned int*]’ at /usr/include/c++/14/bits/stl_algobase.h:548:42,
    inlined from ‘_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false; _II = unsigned int*; _OI = unsigned int*]’ at /usr/include/c++/14/bits/stl_algobase.h:555:31,
    inlined from ‘_OI std::copy(_II, _II, _OI) [with _II = unsigned int*; _OI = unsigned int*]’ at /usr/include/c++/14/bits/stl_algobase.h:651:7,
    inlined from ‘static _ForwardIterator std::__uninitialized_copy<true>::__uninit_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = unsigned int*; _ForwardIterator = unsigned int*]’ at /usr/include/c++/14/bits/stl_uninitialized.h:147:27,
    inlined from ‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = unsigned int*; _ForwardIterator = unsigned int*]’ at /usr/include/c++/14/bits/stl_uninitialized.h:185:15,
    inlined from ‘void fmt::v10::basic_memory_buffer<T, SIZE, Allocator>::grow(size_t) [with T = unsigned int; long unsigned int SIZE = 32; Allocator = std::allocator<unsigned int>]’ at geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/fmt-10.0.0-qyyuwcobqfdlgsootdanxk2vyje6iiyu/include/fmt/format.h:952:28,
    inlined from ‘void fmt::v10::detail::buffer<T>::try_reserve(size_t) [with T = unsigned int]’ at geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/fmt-10.0.0-qyyuwcobqfdlgsootdanxk2vyje6iiyu/include/fmt/core.h:927:39,
    inlined from ‘void fmt::v10::detail::buffer<T>::try_reserve(size_t) [with T = unsigned int]’ at geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/fmt-10.0.0-qyyuwcobqfdlgsootdanxk2vyje6iiyu/include/fmt/core.h:926:24,
    inlined from ‘void fmt::v10::detail::buffer<T>::try_resize(size_t) [with T = unsigned int]’ at geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/fmt-10.0.0-qyyuwcobqfdlgsootdanxk2vyje6iiyu/include/fmt/core.h:918:16,
    inlined from ‘void fmt::v10::basic_memory_buffer<T, SIZE, Allocator>::resize(size_t) [with T = unsigned int; long unsigned int SIZE = 32; Allocator = std::allocator<unsigned int>]’ at geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/fmt-10.0.0-qyyuwcobqfdlgsootdanxk2vyje6iiyu/include/fmt/format.h:1023:63,
    inlined from ‘void fmt::v10::detail::bigint::assign(UInt) [with UInt = long unsigned int; typename std::enable_if<(std::is_same<UInt, long unsigned int>::value || std::is_same<UInt, __int128 unsigned>::value), int>::type <anonymous> = 0]’ at geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/fmt-10.0.0-qyyuwcobqfdlgsootdanxk2vyje6iiyu/include/fmt/format.h:3096:19,
    inlined from ‘void fmt::v10::detail::bigint::operator=(Int) [with Int = int]’ at geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/fmt-10.0.0-qyyuwcobqfdlgsootdanxk2vyje6iiyu/include/fmt/format.h:3117:11,
    inlined from ‘void fmt::v10::detail::format_dragon(basic_fp<__int128 unsigned>, unsigned int, int, buffer<char>&, int&)’ at geos-tpls-path/ubuntu24.04-gcc_tpls/spack/opt/spack/linux-x86_64_v4/fmt-10.0.0-qyyuwcobqfdlgsootdanxk2vyje6iiyu/include/fmt/format.h:3291:11:
/usr/include/c++/14/bits/stl_algobase.h:452:30: error: ‘void* __builtin_memmove(void*, const void*, long unsigned int)’ forming offset 4 is out of the bounds [0, 4] [-Werror=array-bounds=]
  452 |             __builtin_memmove(__result, __first, sizeof(_Tp) * _Num);
      |             ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In static member function ‘static _Up* std::__copy_move<_IsMove, true, std::random_access_iterator_tag>::__copy_m(_Tp*, _Tp*, _Up*) [with _Tp = unsigned int; _Up = unsigned int; bool _IsMove = false]’,
    inlined from ‘_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false; _II = unsigned int*; _OI = unsigned int*]’ at /usr/include/c++/14/bits/stl_algobase.h:521:30,
    inlined from ‘_OI std::__copy_move_a1(_II, _II, _OI) [with bool _IsMove = false; _II = unsigned int*; _OI = unsigned int*]’ at /usr/include/c++/14/bits/stl_algobase.h:548:42,
    inlined from ‘_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false; _II = unsigned int*; _OI = unsigned int*]’ at /usr/include/c++/14/bits/stl_algobase.h:555:31,
    inlined from ‘_OI std::copy(_II, _II, _OI) [with _II = unsigned int*; _OI = unsigned int*]’ at /usr/include/c++/14/bits/stl_algobase.h:651:7,
    inlined from ‘static _ForwardIterator std::__uninitialized_copy<true>::__uninit_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = unsigned int*; _ForwardIterator = unsigned int*]’ at /usr/include/c++/14/bits/stl_uninitialized.h:147:27,
    inlined from ‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = unsigned int*; _ForwardIterator = unsigned int*]’ at /usr/include/c++/14/bits/stl_uninitialized.h:185:15,

[victorapm]

Replaced by #340