Reduce duplicity in GVM analysis (#83250)

Reduce duplicity in GVM analysis (#83250)

There were two very similar pieces of logic in the generic virtual method analysis. First one was deciding whether we need to emit GVM bookkeeping about the type, the second one was deciding whether the type should participate in GVM analysis (the N*M algorithm, "for each type relevant to GVM analysis" * "GVM virtual method called").

Made this into one so that it's in one spot. The interface method resolution is not cheap so this also speeds up the compilation. We should also do this for non-generic virtuals at some point.

I did a test pass with an assert that the analysis came up with the same conclusions to ensure I didn't mess up.