GraphQL - Move epic between board lists

We need a mutation to allow moving epics between board lists, similar to exiting mutation that moves/repositions issues IssueMoveList.

It could be similar to:

mutation {
  epicMoveList(input: { groupPath: "group", iid: "3", boardId: "gid://gitlab/Board/15", fromListId: 6, toListId: 7}) {
    errors
  }
}

We need to create a service for moving an epic and add the mutation.

• Follow-up Issue for repositioning