Draft: feat: JS Parser - Definitions, Imports

This is branched off ruby-parser so I'm mainly just opening this so people can review my code under crates/parser-core/src/javascript. I've currently finished extracting Definitions, and Definition FQNs (some caveats for anonymous functions). I have also added support for imports, but that's still WIP.

I don't intend to merge in this state. Please refer to this new MR, which is a slimmed-down continuation of this closed one.

This branch is now rebased on ruby-definitions (link).

We should wait to review and merge this branch until:

• @michaelangeloio finishes the generic template for extracting defns and refs e.g CodeAnalyzer<G>, and merges in ruby-parser.
• Clarity on what exactly constitutes a Node/Edge for the first iteration of the KG, and what language constructs will not be included in the MVC. This will inform which subsets of imports, and more importantly, which Reference FQN's we will choose to resolve. I believe @jshobrook1 is working on an issue for this discussion right now.
• @michaelangeloio merges in the initial implementation of the library (which ruby-definitions itself will be merged into)