* Fix alias import
Alias importing was registering the alias id as a decl instead of alias.
This caused issues when hiding and then reimporting the alias.
* Clippy format
Co-authored-by: Hristo Filaretov <h.filaretov@protonmail.com>
* Add alias interning
Now, AliasId is used to reference aliases stored in EngineState, similar
to decls, blocks, etc.
* Fix wrong message
* Fix using decl instead of alias
* Extend also alias id visibility
* Merge also aliases from delta
* Add alias hiding code
Does not work yet but passes tests at least.
* Fix wrong alias lookup and visibility appending
* Add hide alias tests
* Fmt & Clippy
* Fix random clippy warnings in "which" command
