mgr/dashboard: support multiple DriveGroups when creating OSDs

mgr/dashboard: support multiple DriveGroups when creating OSDs

The `create_osds` call in orchestrator uses multiple named DriveGroups as
the parameter. Adapt the change in Dashboard.

Some minor polishes:
- Use task manager to wrap the operation.
- The submit button in Preview modal is changed from `Add` to `Create`.
- POST `/api/osd` to create OSDs:
  - Bare OSDs for OSD service container
    {
        "method": "bare",
        "data": {
            "uuid": "xxxx",
            "svc_id": 5
        }
    }

  - OSDs with devices (DriveGroups)

    {
        "method": "drive_groups",
        "data": {
            < drive group spec here>
        }
    }
- `/orchestrator/osd` endpoint is removed.

Fixes: https://tracker.ceph.com/issues/43615
Signed-off-by: Kiefer Chang <kiefer.chang@suse.com>