Add more methods for resolving definitions from AST to their corresponding HIR types

[regexident]

In order to be able to add these methods with consistent naming I had to also rename two existing methods that would otherwise be conflicting/confusing:

Semantics::to_module_def(&self, file: FileId) -> Option<Module> (before)
Semantics::file_to_module_def(&self, file: FileId) -> Option<Module> (after)

Semantics::to_module_defs(&self, file: FileId) -> impl Iterator<Item = Module> (before)
Semantics::file_to_module_defs(&self, file: FileId) -> impl Iterator<Item = Module> (after)

(the PR is motivated by an outside use of the ra_ap_hir crate that would benefit from being able to walk a hir::Function's AST, resolving its exprs/stmts/items to their HIR equivalents)

[Veykril]

@bors r+

[Veykril]

@bors r+

[Veykril]

@bors r+

[Veykril]

@bors r+

[regexident]

Bots having a moment? 😅

[Veykril]

bors is always having a moment

[Veykril]

@bors r+

[bors]

📌 Commit fac8a14 has been approved by Veykril

It is now in the queue for this repository.

[bors]

⌛ Testing commit fac8a14 with merge d8feb90...

[bors]

☀️ Test successful - checks-actions
Approved by: Veykril
Pushing d8feb90 to master...