☂️ Improved code nav for locals and parameters using tree-sitter + SCIP

[varungandhi-src]

Not supported by Squirrel:

• Perl
• Kotlin
• Scala
• Rust

Superseding Squirred:

• Java https://github.com/sourcegraph/sourcegraph/pull/57620
• TypeScript
• JavaScript
• Python
• Ruby
• Go
• C++
• C

Related: https://github.com/sourcegraph/sourcegraph/issues/58005

We should make sure that we're not regressing any functionality compared to Squirrel. Ideally, we can delete Squirrel after this work is complete.

[olafurpg]

Worth noting that w support local variable navigation for several languages via Squirrel https://sourcegraph.com/github.com/sourcegraph/sourcegraph@288f62406a46c2ebf1fbcbc45e9428068cf623a5/-/blob/cmd/symbols/squirrel/languages.go?L70

We might be able to adapt the queries from the code above to work with scip-syntax with fairly minimal effort.

[varungandhi-src]

Closing in favor of https://github.com/sourcegraph/sourcegraph/issues/58726 which has more details.