Improve Project repository storage move workflow

Problem to solve

In #210041 (closed) there is now an API to retrieve a list of all current and historic project repository storage moves and their state. This isn't ideal because the project storage moves are initiated from a project update and it is not possible to see which move is the move that was just initiated without searching through a list.

Proposal

We should provide a new API to directly create project repository storage moves. These moves include their current state and could be polled for updates.

/cc @zj-gitlab