Add support for showing scheduler_hints in server details

Nova currently lacks a straightforward way to expose scheduler hints
associated with a server. This change extends existing Nova's
API to allow users to retrieve this information when it is available.
It adds a new API microversion to support returning the associated
scheduler_hints in ``GET /servers/{server_id}``, `GET /servers/detail``,
``PUT /servers/{server_id}`` and ``POST /server/{server_id}/action``
(rebuild) responses.

Implements: blueprint show-scheduler-hints-in-server-details
Change-Id: If0070cfbc218e0515bf3b58fc8c5067ae22c7072

doc/api_samples/versions/v21-version-get-resp.json

@@ -19,7 +19,7 @@
             }
         ],
         "status": "CURRENT",
-        "version": "2.99",
+        "version": "2.100",
         "min_version": "2.1",
         "updated": "2013-07-23T11:33:21Z"
     }