Atlantis: Add "Unlock All" button to the UI

[kipkoan]

Currently when we upgrade Atlantis, existing plans are lost (immutable infrastructure). To make this a bit less disruptive to people with open PRs, I have been going in and manually releasing the locks on each one through the UI. Atlantis adds a comment on each PR stating that plan will need to be re-run.

It would be nice if either:

1) there was the option to "release all locks" through the UI and/or terminal
2) there was an option to have Atlantis automatically do this when it is being shut down

(This is a stop gap measure until a persistent storage mechanism is in place so that restarting/recreating the Atlantis server doesn't result in data loss.)

[lkysow]

Are you just unlocking them so they get the comment on the pull request that they need to re-plan and aren't confused why an apply fails later?

[kipkoan]

Are you just unlocking them so they get the comment on the pull request that they need to re-plan and aren't confused why an apply fails later?

Yes.

[lkysow]

I don't like the idea of automatically unlocking them on shutdown because if you're persisting the disk then you don't need that to happen.

I think an "unlock all" button on the UI would be the best approach.