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>

.clasp.json.SAMPLE

@@ -0,0 +1,7 @@
+{
+  "rootDir": "dist",
+  "scriptId": "...add scriptId here...",
+  "parentId": [
+    "...spreadsheet/doc url ID here..."
+  ]
+}