Reorganize rust crates into a flat crates directory, simplify some CI steps (#4496)

* 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

crates/cli/src/templates/gitattributes

@@ -0,0 +1,41 @@
+* text=auto eol=lf
+
+# Generated source files
+src/*.json linguist-generated
+src/parser.c linguist-generated
+src/tree_sitter/* linguist-generated
+
+# C bindings
+bindings/c/** linguist-generated
+CMakeLists.txt linguist-generated
+Makefile linguist-generated
+
+# Rust bindings
+bindings/rust/* linguist-generated
+Cargo.toml linguist-generated
+Cargo.lock linguist-generated
+
+# Node.js bindings
+bindings/node/* linguist-generated
+binding.gyp linguist-generated
+package.json linguist-generated
+package-lock.json linguist-generated
+
+# Python bindings
+bindings/python/** linguist-generated
+setup.py linguist-generated
+pyproject.toml linguist-generated
+
+# Go bindings
+bindings/go/* linguist-generated
+go.mod linguist-generated
+go.sum linguist-generated
+
+# Swift bindings
+bindings/swift/** linguist-generated
+Package.swift linguist-generated
+Package.resolved linguist-generated
+
+# Zig bindings
+build.zig linguist-generated
+build.zig.zon linguist-generated