API changes for skipped actions: patch actions and status_message

This patch implements the changes in the API required for the
skipped action blueprint. It includes:

- New field `status_message` is visible in API get calls for Audits,
  ActionPlans and Audits.
- New Patch call is added to `/actions/{action_id}` which allows to
  manually move actions in PENDING state to SKIPPED for ActionPlans
  which have not been started.
- A new API microversion 1.5 is added for these changes.

It also adds requried tests and documentation.

Implements: blueprint add-skip-actions

Assisted-By: Cursor (claude-4-sonnet)

Change-Id: I71fb9af76085e5941a7fd3e9e4c89d6f3a3ada47
Signed-off-by: Alfredo Moralejo <amoralej@redhat.com>

api-ref/source/samples/action-skip-response.json

@@ -0,0 +1,29 @@
+{
+    "state": "SKIPPED",
+    "description": "Migrate instance to another compute node",
+    "parents": [
+        "b4529294-1de6-4302-b57a-9b5d5dc363c6"
+    ],
+    "links": [
+        {
+            "rel": "self",
+            "href": "http://controller:9322/v1/actions/54acc7a0-91b0-46ea-a5f7-4ae2b9df0b0a"
+        },
+        {
+            "rel": "bookmark",
+            "href": "http://controller:9322/actions/54acc7a0-91b0-46ea-a5f7-4ae2b9df0b0a"
+        }
+    ],
+    "action_plan_uuid": "4cbc4ede-0d25-481b-b86e-998dbbd4f8bf",
+    "uuid": "54acc7a0-91b0-46ea-a5f7-4ae2b9df0b0a",
+    "deleted_at": null,
+    "updated_at": "2018-04-10T12:15:44.026973+00:00",
+    "input_parameters": {
+        "migration_type": "live",
+        "destination_node": "compute-2",
+        "resource_id": "a1b2c3d4-e5f6-7890-1234-567890abcdef"
+    },
+    "action_type": "migrate",
+    "created_at": "2018-04-10T11:59:12.725147+00:00",
+    "status_message": "Action skipped by user. Reason:Skipping due to maintenance window"
+}