* The test sources and baselines for these were duplicated in dotnet#15484 to
  test the realsig feature, but that meant that the test _sources_
  needed to be kept in sync by hand. This change uses the approach used
  in dotnet#16795 instead: it reuses the same test _source_ files and just
  adds duplicate _tests_ to check the emitted IL with realsig+.

…realsig-consolidate