mgr/deepsea: DeepSea orchestrator module

mgr/deepsea: DeepSea orchestrator module

This module provides integration between Ceph's orchestrator framework
and DeepSea, a Ceph deployment and management system built upon Salt.

Included so far are implementations of get_inventory() and
describe_service().  This allows `ceph orchestrator device ls`, `ceph
orchestrator service ls` and `ceph orchestrator service status` to
operate correctly.

To test, try:

  # ceph mgr module enable orchestrator_cli
  # ceph mgr module enable deepsea
  # ceph orchestrator set backend deepsea
  # ceph deepsea config-set salt_api_url <salt api url>
  # ceph deepsea config-set salt_api_username <salt api username>
  # ceph deepsea config-set salt_api_password <salt api shared secret>
  # ceph orchestrator device ls
  # ceph orchestrator service ls

Signed-off-by: Tim Serong <tserong@suse.com>