Replace getopt_long with popl.hpp for CLI option parsing

[iareARiES]

Addresses #243

The existing argument parsing in main() used getopt_long, which required maintaining three separate places in sync for every option — the static struct option array, the switch-case block, and the manual if (do_help) help text. Adding or changing any option meant updating all three. The help text was entirely hand-written, so it could silently go out of sync with the actual options.

What I changed

Only package/src/prmon.cpp was modified:

• Swapped #include <getopt.h> for #include "popl.hpp"
• Removed the long_options[] array, the getopt_long while loop, and the ~60 line manual help block
• Replaced them with a popl::OptionParser registering all 12 options in one place
• The -- separator scan is preserved — argv is scanned for -- before op.parse() so child program arguments are never consumed by popl
• Repeatable options (--netdev, --disable, --level) are handled via count()/value(idx) loops
• All post-parse logic (env variable handling, logger setup, pid/child dispatch) is unchanged

popl.hpp was vendored as a single header at package/include/popl.hpp — no new external dependency.

Behavior

No functional changes intended. Verified:

• All 14 existing tests pass (ctest 14/14)
• --pid mode works
• -- prog ... mode works
• Repeatable options behave as before
• Argument validation semantics unchanged

The CodeFactor issue is in popl.hpp itself (a vendored third-party header), not in any code introduced by this PR.

[iareARiES]

Hi @graeme-a-stewart , this PR is ready for review. Please let me know if any changes are required.

[graeme-a-stewart]

Thank you @iareARiES. I have been in a workshop this week, but next week I will review this.

[graeme-a-stewart]

Just a quick observation - you have committed some files that should not be in the repository. Please remove them. Thanks.

[iareARiES]

@graeme-a-stewart Thanks for pointing that out.
Removed the generated files and updated the branch accordingly.