Make implementation of IExecutionContext independent from DLL

[mtyrolski]

Written additional possibility for getting build version of the running service.

• Deducing manifest file and getting build version:

protected static string? GetBuildVersionFromServiceManifest()

[mtyrolski]

 System.TypeInitializationException: The type initializer for 
'Microsoft.Omex.Extensions.Hosting.Services.UnitTests.MockServiceFabricServices' threw an exception. ---> 
System.IO.FileNotFoundException: Could not load file or assembly 'C:\Program Files\Microsoft Service 
Fabric\bin\Fabric\Fabric.Code\NS_8\Microsoft.ServiceFabric.Data.Impl.dll'. The system cannot find the path specified.

    Test method Microsoft.Omex.Extensions.Hosting.Services.Remoting.UnitTests.HostBuilderExtensionsTests.AddRemotingListener_ToStatelessServiceUsingIServiceTypeThatHasRegisteredDependencies_BuildDoesNotThrow threw exception: 
    System.TypeInitializationException: The type initializer for 'Microsoft.Omex.Extensions.Hosting.Services.UnitTests.MockServiceFabricServices' threw an exception. ---> System.IO.FileNotFoundException: Could not load file or assembly 'C:\Program Files\Microsoft Service Fabric\bin\Fabric\Fabric.Code\NS_8\Microsoft.ServiceFabric.Data.Impl.dll'. The system cannot find the path specified.
  Stack Trace: 
    AssemblyLoadContext.LoadFromPath(IntPtr ptrNativeAssemblyLoadContext, String ilPath, String niPath, ObjectHandleOnStack retAssembly)
    AssemblyLoadContext.LoadFromAssemblyPath(String assemblyPath)
    Assembly.LoadFrom(String assemblyFile)
    ReliableStateManager.ctor(StatefulServiceContext serviceContext, ReliableStateManagerConfiguration configuration)
    StatefulService.ctor(StatefulServiceContext serviceContext)
    OmexStatefulService.ctor(OmexStatefulServiceRegistrator serviceRegistrator, StatefulServiceContext serviceContext) line 24
    MockServiceFabricServices.cctor() line 28
    --- End of inner exception stack trace ---
    MockServiceFabricServices.get_MockOmexStatelessService() line 17
    HostBuilderExtensionsTests.AddRemotingListener_ToStatelessServiceUsingIServiceTypeThatHasRegisteredDependencies_BuildDoesNotThrow() line 114

[AndreyTretyak]

This change was started to handle a possible scenario of making SF service build number independent from dll build number.
Currently, there is no plan of making the service version independent, so I think we should not merge this change as it reduces replayability due to dependency on the SF cluster folder structure. But we can leave it for future reference if the need ever arises.