Improve the renderign of new and existing discussions
by reducing the number of watchers on each object & array.
Previously every discussion change would trigger an update for every
discussion component.

Also tidied up some components to get them closer to our docs.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/51506

Instead of relying on a global method, we now emit an event on the MR
widget that tells it to check the status

After resolving a discussion on a merge request page the merge request
widget state would not get updated meaning users would need to refresh
the page to merge (if that option is enabled in the projects settings)

https://gitlab.com/gitlab-org/gitlab-ce/issues/42882

added spec for polling

Add loading button for better UX

Formats dates
Fixes clipboard button
Simplifies HTML