Fetch metadata and media content via MediaBrowser instead of directly from Frigate server

[dermotduffy]

• Use the MediaBrowser to search for clips/snapshots.
• Use the MediaBrowser to resolve and HomeAssistant to proxy the clip/snapshot content.
• Frigate URL option becomes optional and is only used for the Frigate UI menu button (if URL not set, button will be hidden to reduce button clutter).
• Highlight when motion is detected with a different color as part of a menu refactor.

=> This should be the "proper fix" for those without a reverse proxy, or those who are using Nabu Casa .

Closes #13
Closes #19
Closes #20
Closes #24

[github-actions]

🎉 HACS repository validator action summary 🎉
✅ The repository is not archived
✅ hacs.json has the 'name' key set
✅ The repository has a description
✅ The repository has topics
✅ The repository has issues enabled
✅ This day ends with an 'y' (Sunday)
✅ README.md exists
✅ Information file has images
⚪ Ignored check: hacs