Add watch option

Author: ncalteen

package-lock.json

@@ -31,6 +31,7 @@
     "format:check": "npx prettier --check .",
     "lint": "npx eslint .",
     "package": "npx rollup --config rollup.config.ts --configPlugin @rollup/plugin-typescript",
+    "package:watch": "npx rollup --config rollup.config.ts --configPlugin @rollup/plugin-typescript --watch",
     "test": "NODE_OPTIONS=--experimental-vm-modules NODE_NO_WARNINGS=1 npx jest",
     "all": "npm run format:write && npm run lint && npm run test && npm run coverage && npm run package"
   },