Mark .overrides from marked methods in a copy assembly (#82197)

Mark .overrides from marked methods in a copy assembly (#82197)

Fixes #81746

Static abstract interface methods that aren't used are expected to be removed, and any references to them in the metadata of the overriders are expected to be removed in SweepStep. However, overrides may come from a 'copy' assembly, so their metadata won't get swept at all. We would still remove the static abstract method, but would leave the reference to it in the overrider's metadata, creating invalid metadata.

This fixes the issue by making sure all methods referenced in the .overrides metadata of method X are marked if method X is in a copy assembly, where previously we would postpone marking the .overrides if the base was static abstract.