chore(examples): migrates email example to 3.0 [skip-lint] (#9215)

Changes:

- Migrates `email` example project to `3.0` from `2.0`
- Replaces `inline-css` dependency with `juice` package instead.
- Replaces `Handlebars` dependency with `ejs` package instead.

Reason for replacing packages:
- Both `inline-css` & `Handlebars` had issues with Nextjs and its
Webpack bundling i.e does not support `require.extensions`.
- `ejs` & `juice` do not rely on `require.extensions`.

.github/workflows/main.yml

@@ -49,6 +49,7 @@ jobs:
               - 'pnpm-lock.yaml'
               - 'package.json'
               - 'templates/**'
+              - 'examples/**'
             templates:
               - 'templates/**'
       - name: Log all filter results