Auto merge of #144272 - petrochenkov:disambunder2, r=oli-obk

resolve: Make disambiguators for underscore bindings module-local (take 2)

The difference with rust-lang/rust#144013 can be seen in the second commit.

Now we just keep a separate disambiguator counter in every `Module`, instead of a global counter in `Resolver`.
This will be ok for parallel import resolution because we'll need to lock the module anyway when updating `resolutions` and other fields in it.
And for external modules the disabmiguator could be just passed as an argument to `define_extern`, without using any cells or locks, once rust-lang/rust#143884 lands.

Unblocks rust-lang/rust#143884.

Author: bors