Summary

Part of #9618

This PR sets the foundations of go-to definition and implements part of the logic.

• Added editor settings
• Added conditional enabling via settings handle
• Added dynamic registration of the capability
• Features currently implemented
  • Simple JS binding detection and go-to in file and in another file
  • Simple class/className string detection of JSX attributes and HTML attributes, with go to the same file or another file

How it works

I added a new editor capability to the list. This new type now contains two functions, which are essentially two side of the same coin:

• resolve_reference: essentially, when the cursor hovers over an entity, we resolve it against the CST of the document and its snippets. If we support it, we then return information such as the file path and the text range. Each language implements this function. Here, we also return a DefinitionReference that says: the reference is here (checked against the semantic model), the reference has been imported (via JS import for now, but it's been left generic), or the reference is a CSS string.
• resolve_definition: It's the function that tries to find where the entity has been defined. It uses a mix of module graph and semantic model, depending on what we're looking for.

The module graph has been modified. We now store the content offset of the CSS snippets found in the HTML document. This information is needed so that, when we resolve the style definition, we can compute the correct offset.

Test Plan

Added plenty of tests.
Manually tested with Zed. It works like a charm for the things we're implementing.
Happy to share a recording if you want.

CI won't run, but I checked that just l and just f work. And all tests pass.

I refactored the tests of server.tests.ts because it was becoming a 2k lines of tests. I moved all the navigation tests into its own file, and added a new file to share the common utilities

Docs