Webpack 5 support with updated packages (#131)

- Update to Webpack 5
- Use @effortlessmotion dynamic html and inline source plugins
- Remove .clasp.json and use SAMPLE file
- Consistent prettier formatting throughout
- Update packages to latest versions

Co-authored-by: Kevin Malakoff <kmalakoff@gmail.com>

README.md

@@ -113,7 +113,7 @@ You will need to update the `.clasp.json` file in the root of this project with
 {
   "scriptId": "1PY037hPcy................................................",
   "parentId": ["1Df30......................................."],
-  "rootDir": "./dist"
+  "rootDir": "dist"
 }
 ```