10423: Internal: refactor for mdbook plugin r=Veykril a=HKalbasi
This PR is for upstreaming changes that I made for mdbook plugin. Changes are adding inlay hints to `StaticIndex` and changing some functions for working around privacy of crates.
Aside this, is it okay if I bring the plugin in tree? It is a simple binary crate. I feel it will better maintained here and become resistant to api changes.
Co-authored-by: hamidreza kalbasi <hamidrezakalbasi@protonmail.com>
This renames `descend_into_macros` to `descend_into_macros_single` and `descend_into_macros_many` into `descend_into_macros`.
However, this does not touch a function in `SemanticsImpl` of same name.
