fe61575228
Create some minimal HIR for associated opaque types `LocalDefId`s for opaque types in traits and impls are created after AST -> HIR lowering, so they don't have corresponding HIR and return their various properties through fed queries. In this PR I also feed some core HIR-related queries for these `LocalDefId`s (which happen to be HIR owners). As a result all `LocalDefId`s now have corresponding `HirId`s and HIR nodes, and "optional" methods like `opt_local_def_id_to_hir_id` and `opt_hir_node_by_def_id` can be removed. Follow up to https://github.com/rust-lang/rust/pull/120206.
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.