Merge #10284

10284: internal: definition based hover functions r=Veykril a=HKalbasi

This is part of #10181 but since it is blocked and `hover.rs` is moving quickly so will cause conflicts, I submitted this PR.

This PR extract some parts of `hover` to `find_definition` (maybe this need to be moved to some other file?) and `hover_for_definition`, with those functions I will be able to calculate definition of every token, and calculate hover (and probably other queries) for each definition only once.

Co-authored-by: hamidreza kalbasi <hamidrezakalbasi@protonmail.com>