* Move all rust crates (except lib) into crates dir, w/o nesting
* Remove stale path from .gitattributes
* Rename lib.rs files for easier navigation
* Rename mod.rs file for easier navigation
* Fix emscripten-version path
* Fix fixtures dir paths
* Use the default rustfmt settings
* Don't use nightly on CI
It is very common practice to ignore
these lock files for libraries, since they do not apply to applications
that use the libraries. The lock files are especially not useful in
tree-sitter grammar repos, since tree-sitter grammars should not have
dependencies. The lock files are just a source of merge conflicts and
spurious CI failures.