迁移 tablet

Request

GET /api/tablet_migration?goal={enum}&tablet_id={int}&schema_hash={int}&disk={string}

在 BE 节点上迁移单个 tablet 到指定磁盘

无

    {
        status: "Success",
        msg: "migration task is successfully submitted."
    }

或

    {
        status: "Fail",
        msg: "Migration task submission failed"
    }

    {
        status: "Success",
        msg: "migration task is running",
        dest_disk: "xxxxxx"
    }

或

    {
        status: "Success",
        msg: "migration task has finished successfully",
        dest_disk: "xxxxxx"
    }

或

    {
        status: "Success",
        msg: "migration task failed.",
        dest_disk: "xxxxxx"
    }

```shell
curl "http://127.0.0.1:8040/api/tablet_migration?goal=run&tablet_id=123&schema_hash=333&disk=/disk1"

```