Add action_response into .fleet-actions-results mapping (#79584)

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

x-pack/plugin/core/src/main/resources/fleet-actions-results.json

@@ -23,6 +23,10 @@
           "enabled": false,
           "type": "object"
         },
+        "action_response": {
+          "dynamic": true,
+          "type": "object"
+        },
         "data": {
           "enabled": false,
           "type": "object"