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

api-ref/source/parameters.yaml

@@ -6127,6 +6127,14 @@ running_vms_total:
   in: body
   required: true
   type: integer
+scheduler_hints:
+  description: |
+    The dictionary of hints sent to the scheduler during server
+    creation time.
+  in: body
+  required: true
+  type: object
+  min_version: 2.100
 secgroup_default_rule_id:
   description: |
     The security group default rule ID.