Alerting: Support for optimistic concurrency in priovisioning Tempate API (#91195)

* support optimistic concurrency in template service

* update request handler to get version from query parameter

* return not found if a new template is set with version

* update PUT api to set version

* update documentation + for mute timings

---------

Co-authored-by: brendamuir <100768211+brendamuir@users.noreply.github.com>

pkg/services/ngalert/api/tooling/spec.json

@@ -3393,6 +3393,12 @@
             "schema": {
               "$ref": "#/definitions/ValidationError"
             }
+          },
+          "409": {
+            "description": "GenericPublicError",
+            "schema": {
+              "$ref": "#/definitions/GenericPublicError"
+            }
           }
         }
       },
@@ -3406,15 +3412,27 @@
         "parameters": [
           {
             "type": "string",
-            "description": "Template Name",
+            "description": "Template name",
             "name": "name",
             "in": "path",
             "required": true
+          },
+          {
+            "type": "string",
+            "description": "Version of template to use for optimistic concurrency. Leave empty to disable validation",
+            "name": "version",
+            "in": "query"
           }
         ],
         "responses": {
           "204": {
             "description": " The template was deleted successfully."
+          },
+          "409": {
+            "description": "GenericPublicError",
+            "schema": {
+              "$ref": "#/definitions/GenericPublicError"
+            }
           }
         }
       }
@@ -5880,6 +5898,9 @@
         },
         "template": {
           "type": "string"
+        },
+        "version": {
+          "type": "string"
         }
       }
     },
@@ -5888,6 +5909,9 @@
       "properties": {
         "template": {
           "type": "string"
+        },
+        "version": {
+          "type": "string"
         }
       }
     },