Findscript.cmake.in enhancements

[smanders]

the find script template has some checks:

• verify the find script that's installed matches the one being used by the project
• the linux distribution used to build the install matches the distribution being used by the project

https://github.com/smanders/externpro/blob/21.04/modules/Findscript.cmake.in#L100-L127

it would be nice to simplify the find script so that it just calls a function (in externpro's xpfunmac.cmake) so that every time these checks are enhanced it doesn't mean that the find script has to be updated in every project that uses it

and it would be nice to add to the checks: record the MSVC_VERSION https://cmake.org/cmake/help/latest/variable/MSVC_VERSION.html used to build externpro (internpro, webpro, pluginsdk as well) and compare it to the version being used to build the project

[smanders]

completed with commits referenced above