Add basic validation for project import from Bitbucket Cloud
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There is a [closed MR](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/50612) from a ~"Community contribution" that added a new spec file for importing a project from Bitbucket Cloud.
The MR got stale and the team didn't have capacity to wrap up the remaining work. Let's continue work on adding basic validation for the above mentioned use case.
/cc @acunskis
issue