Synced from eclipse/che issue

https://github.com/eclipse/che/issues/21949

Is your enhancement related to a problem? Please describe

Users want to use OAuth 2.0 with BitBucket.

Describe the solution you'd like

Support OAuth2, as we do for Git:
https://www.eclipse.org/che/docs/stable/administration-guide/configuring-oauth-2-for-github/

Instead of just OAuth1, as we currently provide for BitBucket:
https://www.eclipse.org/che/docs/stable/administration-guide/configuring-oauth-1-for-a-bitbucket-server/

Additional context

Enterprise customers are making the request, please give it good consideration. Thank you!

Release Notes Text

Atlassian Bitbucket Server has recently added the support for OAuth v2.0 for access delegation (previously only OAuth v1 was supported). Eclipse Che now supports both OAuth v2.0 and v1.0 applications to automatically mount and configure developers Bitbucket personal access tokens.