Enforced Merge Request

ZD: https://gitlab.zendesk.com/agent/tickets/21076

Description

Currently a kind of a way to do that is with the permission structure that some people do have developer permission and some do have master permissions. Unfortunately, this is not a suitable solution. E.g. one reason is that a master is always able to push directly to the protected branch. Another reason is that the permission management get much more complicated. Who should get master permissions and who should get developer permissions. We want to keep the permission structure as flat as possible.