refactor(ast_tools): re-vamp oxc_ast_tools

[overlookmotel]

Large refactor of oxc_ast_tools. This barely alters the generated code which oxc_ast_tools produces, but it overhauls its internals significantly.

Notable changes:

• Code and types are much simplified.
• Fully documented.
• Schema is the single source of truth for information about the AST. Generators don't have to deal with the complicated syn types.
• Vecs, Options, Boxes, and primitive types have their own entries in the schema.
• Co-locate logic for custom attributes (e.g. #[visit]) with the generators which use those attributes.
• Helpers for parsing attributes, and other common actions.
• Fix logic for calculating type layouts, correctly calculating niches.
• Generation runs in parallel with rayon.

Overall intent is to make maintaining/modifying the existing generators, and adding new ones, much easier. The complex logic of parsing types etc is abstracted away into the "framework" of oxc_ast_tools, leaving the generators themselves simpler to write and easier to reason about.

[overlookmotel]

• refactor(ast_tools): re-vamp oxc_ast_tools #8844 👈 (View in Graphite)
• main

---

How to use the Graphite Merge Queue

Add either label to this PR to merge it via the merge queue:

• 0-merge - adds this PR to the back of the merge queue
• hotfix - for urgent hot fixes, skip the queue and merge this PR next

You must have a Graphite account in order to use the merge queue. Sign up using this link.

An organization admin has enabled the Graphite Merge Queue in this repository.

Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue.

This stack of pull requests is managed by Graphite. Learn more about stacking.

[codspeed-hq]

CodSpeed Performance Report

Merging #8844 will not alter performance

_{Comparing 02-02-refactor_ast_tools_re-vamp_oxc_ast_tools_ (1450dca) with main (9c84c6d)}

Summary

✅ 33 untouched benchmarks