Refactor projectplugin quick-dialogs
This is an effort to refactor quick dialogs in project plugin (for now). As a result we have
- Less code duplication
- Fix line edit clearing triggers refiltering of the model (not a big deal if there isn't too much data)
- Fix double reload of a project because we have a file watcher + a signal/slot notifying branch change.
- Branch dialog is created on the fly now. No state is stored.