Introduce group-level protected branches

What does this MR do and why?

Releasing Group-level protected branches MVC (&8679) Closes [Feature flag] Rollout of allow_protected_branc... (#383178 - closed)

Introduce group-level protected branches

We have implemented group-level settings to manage protected branches for all projects within a group.

This feature is only available on top-level groups with premium and ultimate licenses.

Group owners can now create protected branch configurations within the group's repository settings. These protected branches are applied to all projects within this group and are applied in addition to the project-level protected branches.

Changelog: added EE: true

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