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/watcher-api-v1-audits.inc

@@ -85,6 +85,7 @@ version 1:
     - start_time: audit_starttime_resp
     - end_time: audit_endtime_resp
     - force: audit_force
+    - status_message: audit_status_message
 
 **Example JSON representation of an Audit:**
 
@@ -184,6 +185,7 @@ Response
     - start_time: audit_starttime_resp
     - end_time: audit_endtime_resp
     - force: audit_force
+    - status_message: audit_status_message
 
 **Example JSON representation of an Audit:**
 
@@ -231,6 +233,7 @@ Response
     - start_time: audit_starttime_resp
     - end_time: audit_endtime_resp
     - force: audit_force
+    - status_message: audit_status_message
 
 **Example JSON representation of an Audit:**
 
@@ -286,6 +289,7 @@ version 1:
     - start_time: audit_starttime_resp
     - end_time: audit_endtime_resp
     - force: audit_force
+    - status_message: audit_status_message
 
 **Example JSON representation of an Audit:**
 
@@ -341,6 +345,7 @@ Response
     - start_time: audit_starttime_resp
     - end_time: audit_endtime_resp
     - force: audit_force
+    - status_message: audit_status_message
 
 **Example JSON representation of an Audit:**