Auto merge of rust-lang#103530 - cjgillot:hir-lifetimes-direct, r=estebank

Resolve lifetimes independently for each item-like.

Now that the heavy-lifting is done on the AST and during lowering, we do not need to perform HIR lifetime resolution on a full item at once.  Instead, we can treat each item-like independently, and look at `generics_of` the parent exceptionally for associated items.

Author: bors