resolve: Support imports of associated types and glob imports from traits
Follow up to https://github.com/rust-lang/rust/pull/134754, part of https://github.com/rust-lang/rust/issues/134691.
This PR also closes https://github.com/rust-lang/rust/issues/138711 now.
Prohibiting `use Trait::AssocType;` at name resolution stage doesn't make sense, the name itself is perfectly resolveable.
It's a type checker's problem that the necessary generic args are not passed when the imported `AssocType` is used, so an error should be reported there.
And since we can import associated trait items now, glob imports from traits can also be allowed.
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