Bitbucket Cloud: Add Launchpad Support

[sergeibbb]

• Add support for seeing Bitbucket PRs in Launchpad.

(parent #3916, related #3995, a follow-up #4128)

Testing notes

• Bitbucket pull requests are loaded and categorized

• Globe icon shows "Open on Bitbucket" and opens the right page
  

• Items are categorized and the current branch is detected

  • 
  • Review requested:
    
  • Approved:
    
  • Changes requested:
    

• Item actions work:

  • Open in Worktree
  • Switch to Branch
  • Open in Commit Graph
  • Merge

• Pin and snooze work:

  • Pinning, snoozing, unpinning, unsnoozing in GitLens gets reflected on GKDev
  • Pinning, snoozing, unpinning, unsnoozing on GKDev gets reflected in GitLens
  • It's reflected in Launchpad (especially after a restart),
  • On Home make sure snoozed stuff doesn't enter the summary:

snoozing-bitbucket-home-reflected.mp4