chore: Add documentation pages for the Bitbucket SAAS OAuth flow

[vinokurig]

Signed-off-by: Igor Vinokur [email protected]

What does this pull request change?

Add instructions how to configure Bitbucket SAAS OAuth flow

What issues does this pull request fix or reference?

https://github.com/eclipse/che/issues/21517

Specify the version of the product this pull request applies to

7.51

Pull Request checklist

The author and the reviewers validate the content of this pull request with the following checklist, in addition to the automated tests.

• Any procedure:
  • [ ] Successfully tested.
• Any page or link rename:
  • [ ] The page contains a redirection for the previous URL.
  • Propagate the URL change in:
    • [ ] Dashboard default branding data
    • [ ] Chectl constants.ts
• [ ] Builds on Eclipse Che hosted by Red Hat.
• [ ] the Validate language on files added or modified step reports no vale warnings.

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[ibuziuk]

@max-cx could you please review?

[max-cx]

Requires backporting to the 7.52.x branch.