package.json: Add format and format-check scripts

I believe this were accidentally removed when I regenerated bindings
using a newer tree-sitter CLI.

Author: the-mikedavis

package.json

@@ -8,7 +8,9 @@
     "install": "node-gyp-build",
     "prestart": "tree-sitter build --wasm",
     "start": "tree-sitter playground",
-    "test": "node --test bindings/node/*_test.js"
+    "test": "node --test bindings/node/*_test.js",
+    "format": "prettier --trailing-comma es5 --write grammar.js",
+    "format-check": "prettier --trailing-comma es5 --check grammar.js"
   },
   "repository": {
     "type": "git",