Keep closed PRs option

- Migrated “merged” boolean into “condition” field for PullRequest objects, can have many values, default “open”
- Refactored code to use this property
- Added “remove closed” option to UIs
- Added code in merge detection to also mark a PR as closed if the user wants this
- Created “PR Closed” notifications
- Added a step when opening the app where all the PR post processing is run once just in case
- Using this PR as testing for this feature, expect a lot of open/close spam below