Add Bitbucket Cloud support for multi-branch Pipeline

Created by: LinuxSuRen

What would you like to be added: Currently, only Bitbucket Server supported.

/area devops /priority high /cc @kubesphere/sig-devops

Changes proposal There're a couple of things that might need to change:

• Change the Tab text from Bitbucket Server to Bitbucket
• Do not check the server address if it's https://bitbucket.org or https://bitbucket.org/
  • It means do not call API v1alpha2/scms/bitbucket-server/servers
• Change the API calling from v1alpha2/scms/bitbucket-server/verify/ to v1alpha2/scms/bitbucket-cloud/verify/ if the address is https://bitbucket.org or https://bitbucket.org/

Why is this needed: Bitbucket Cloud is popular among some users. And it's not difficult to support it.