Bitbucket Cloud: Set Up Auth Provider and Basic Integration

[sergeibbb]

• Add as a cloud auth provider
• Set up basic integration with connect/disconnect
• Show as a provider in home integrations list

(parent #3916, next #4045, related (azure) #3976)

Testing notes

• Connection flow and displaying in list of integrations on Home:

• Displaying the rich integration status in remotes:

During testing check that:

• connect flow through remotes works. steps:
  • disconnect on GKDev, sync on Home
  • go to remotes
  • click "connect", pass through the flow.
  • the result should be reflected both: on remotes and on Home.
• disconnecting on GKDev is reflected on Home after the sync