chore: add dev script for tsc --watch

Author: NathanWalker

package.json

@@ -32,6 +32,7 @@
     "clean": "npx rimraf node_modules package-lock.json && npm run setup",
     "build": "grunt",
     "build.all": "grunt test",
+    "dev": "tsc --watch",
     "setup": "npm i --ignore-scripts --legacy-peer-deps && npm rebuild husky",
     "test": "mocha --config=test/.mocharc.yml",
     "postinstall": "node postinstall.js",