fix: jump to correct definition when names overlap

[mhuisi]

Fixes #1170.

This PR adds the module name to RefIdent in order to distinguish conflicting names from different files. This also fixes related issues in find-references or the call hierarchy feature. It also adds some docstrings and stylistically refactors a bunch of code.

[leanprover-community-mathlib4-bot]

Mathlib CI status (docs):

• ❗ Std CI can not be attempted yet, as the nightly-testing-2024-03-08 tag does not exist there yet. We will retry when you push more commits. If you rebase your branch onto nightly-with-mathlib, Std CI should run now. (2024-03-12 13:51:56)
• ❗ Std/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 68eaf33e86689e3f303d38e2f071b5e8b7fd172f --onto 317adf42e92a4dbe07295bc1f0429b61bb8079fe. (2024-03-14 15:46:32)

[mhuisi]

!bench

[leanprover-bot]

Here are the benchmark results for commit f0c2bd445e1781ee9dc08652e12893eecf2beca8. There were significant changes against commit ccac989ddab7aa0827c16f355c3cf305aa65fa8a:

  Benchmark   Metric       Change
  =========================================
+ stdlib      wall-clock    -1.2% (-14.3 σ)

[m4lvin]

Thank you so much, this will make my current project a lot easier to work with :-)