Inherit project-level approval rules on MR creation via API

Problem to solve

When an MR is created via API and the project has approval rules, they won't be inherited automatically.

Intended users

Developers

Further details

The behavior via API is different from the behavior on the web UI. It's confusing and to achieve the same result as the web UI, API user have to manually recreate the project-level rules as MR-level rules which can be tedious.

Proposal

Modify the create MR API endpoint to automatically re-create project-level rules as MR-level rules.

Permissions and Security

Permissions of the API should be consistent with interface permissions of the user performing the operation.

Documentation

Update the Merge Requests and Approvals API documentation