Update extension to support new commit view

[pierremtb]

Only for users with Preview features enabled I believe at this time.

[pierremtb]

This has now been reported by @maxammann to cause CSS issues across all github when the extension is enabled. The extension in its form has been temporarily unpublished from the store. A rewrite leveraging more modern Zoo APIs and integrating properly with Github's new UI is needed before we can publish this again.