Grant permissions for oauth users based on scopes

Igor Drozdovrequested to merge
id-grant-abilities-for-oauth-users into master

What does this MR do and why?

The permissions are granted based on this mapping: https://gitlab.com/gitlab-org/gitlab/-/blob/32fe1691b9f9f3c3272cd2328f50971f0afd47b1/lib/gitlab/auth.rb#L240

Related issue: #321359 (closed)

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