Auto merge of #89239 - petrochenkov:modcache, r=cjgillot

Auto merge of #89239 - petrochenkov:modcache, r=cjgillot

resolve: Cache module loading for all foreign modules

It was previously cached for modules loaded from `fn get_module`, but not for modules loaded from `fn build_reduced_graph_for_external_crate_res`.
This also makes all foreign modules use their real parent, span and expansion instead of possibly a parent/span/expansion of their reexport.
Modules are also often compared using referential equality (`ptr::eq`), this change makes such comparisons correct in all cases.

An ICE happening on attempt to decode expansions for foreign enums and traits is avoided.

Also local enums and traits are now added to the module map.

Follow up to https://github.com/rust-lang/rust/pull/88872.
r? `@cjgillot`