API for configuring repository pull mirroring via HTTP

Using the API, one can create a Project and set an import_url but Repository Mirroring can not be turned on via the API. We should provide an API for managing pull mirroring.

Proposal

Because multiple push mirroring targets are supported, the API should be designed so that it works for both

• Add an API to configure pull mirroring PUT /projects/{project_id}/mirror

{ "todo": "todo" } ```

• Add an API to disable pull mirroring DELETE /projects/{project_id}/mirror/{id}
• Add an API to list mirroring target GET /projects/{project_id}/mirror

Links / references

Here is where the customer asked about it https://gitlab.zendesk.com/agent/tickets/55517