Move test_fx_ver under the cli/test folder

[vitek-karas]

Once dotnet/core-setup#5522 is merged we will have the "test exe" infrastructure in place. So it would make sense to move the test_fx_ver under the test folder and cleanup the cmake file to use the shared bits.

@sdmaclea @elinor-fung

[elinor-fung]

This was done in #49313.