This PR changes the GitHub action workflow for V4 to start running all
unit tests and build on both Ubuntu (our current default) _and_ Windows.
This is to ensure we catch issues with paths and other Windows-specific
things sooner. It does, however, not replace testing on Windows.
* run `pnpm update --recursive`
* update tests to reflect lightningcss bump
It looks like it's mainly (re-)ordering properties. Not 100% sure why
though.
* move `oxide/crates` to `crates`
* ignore `target/` folder
* ensure pnpm points to `crates` instead of `oxide/crates`
* ensure all paths point to `crates` instead of `oxide/crates`
* update `oxide/crates` -> `crates` path in workflows
* use correct path in .prettierignore
* rename `crates/core` to `crates/oxide`
* remove oxide folder
* fix test script to run `cargo test` directly
