Add YouTube embed fallback styling

[ShayPunter]

Fixes #6193

Changes proposed in this pull request:

• Implements some fallback styling for d.c.c. for youtube lite

How to test

1. Clone webdev-infra and checkout branch 6193_youtube_embed_should_show_fallback_link
2. Clone d.c.c repository and checkout branch 6193_youtube_embed_should_show_fallback_link_when_js_is_disabled
3. Setup a sym link between the webdev-infra and d.c.c repository
4. Navigate to /blog/new-in-chrome-113/ with javascript enabled, you should see the youtube video as expected
5. Disable javascript
6. Refresh the page, you should now see the fallback text in place of the youtube video

[chrome-devrel-infra]

✅ Preview (static) for commit 9b16582 available at https://pr-6271-static-dot-dcc-staging.uc.r.appspot.com/.