[v8.5.x] Alerting: Provisioning message templates (#48789)

* Alerting: Provisioning message templates (#48665)

* Generate API for writing templates

* Persist templates app logic layer

* Validate templates

* Extract logic, make set and delete methods

* Drop post route for templates

* Fix response details, wire up remainder of API

* Authorize routes

* Mirror some existing tests on new APIs

* Generate mock for prov store

* Wire up prov store mock, add tests using it

* Cover cases for both storage paths

* Add happy path tests and fix bugs if file contains no template section

* Normalize template content with define statement

* Tests for deletion

* Fix linter error

* Move provenance field to DTO

* empty commit

* ID to name

* Fix in auth too

(cherry picked from commit 0f56462fbe)

* ErrorContains -> Error then Contains

Co-authored-by: Alexander Weaver <weaver.alex.d@gmail.com>

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

@@ -1315,7 +1315,7 @@
         }
       }
     },
-    "/api/provisioning/templates/{ID}": {
+    "/api/provisioning/templates/{name}": {
       "get": {
         "tags": [
           "provisioning"
@@ -1330,6 +1330,48 @@
             "$ref": "#/responses/NotFound"
           }
         }
+      },
+      "put": {
+        "consumes": [
+          "application/json"
+        ],
+        "tags": [
+          "provisioning"
+        ],
+        "summary": "Updates an existing template.",
+        "operationId": "RoutePutTemplate",
+        "parameters": [
+          {
+            "name": "Body",
+            "in": "body",
+            "schema": {
+              "$ref": "#/definitions/MessageTemplateContent"
+            }
+          }
+        ],
+        "responses": {
+          "202": {
+            "$ref": "#/responses/Accepted"
+          },
+          "400": {
+            "description": "ValidationError",
+            "schema": {
+              "$ref": "#/definitions/ValidationError"
+            }
+          }
+        }
+      },
+      "delete": {
+        "tags": [
+          "provisioning"
+        ],
+        "summary": "Delete a template.",
+        "operationId": "RouteDeleteTemplate",
+        "responses": {
+          "204": {
+            "$ref": "#/responses/Accepted"
+          }
+        }
       }
     },
     "/api/ruler/grafana/api/v1/rules": {
@@ -3287,6 +3329,15 @@
       },
       "$ref": "#/definitions/Matchers"
     },
+    "MessageTemplateContent": {
+      "type": "object",
+      "properties": {
+        "Template": {
+          "type": "string"
+        }
+      },
+      "x-go-package": "github.com/grafana/grafana/pkg/services/ngalert/api/tooling/definitions"
+    },
     "MonthRange": {
       "type": "object",
       "title": "A MonthRange is an inclusive range between [1, 12] where 1 = January.",
@@ -5480,6 +5531,7 @@
       "$ref": "#/definitions/postableSilence"
     },
     "receiver": {
+      "description": "Receiver receiver",
       "type": "object",
       "required": [
         "name"
@@ -5491,8 +5543,6 @@
           "x-go-name": "Name"
         }
       },
-      "x-go-name": "Receiver",
-      "x-go-package": "github.com/prometheus/alertmanager/api/v2/models",
       "$ref": "#/definitions/receiver"
     },
     "silence": {