Alerting: MuteTiming service return errutil + GetTiming by name (#79772)

* add get mute timing by name to MuteTimingService
* update get mute timing request handler to use the service method

* replace validation, uniqueness and used errors with errutils
* update mute timing methods return errutil responses
* use the term "time interval" in errors bevause mute timings are deprecated in Alertmanager and will be replaced by time intervals in the future.

* update create and update methods to return struct instead of pointer

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

@@ -1281,6 +1281,14 @@
    "title": "Frames is a slice of Frame pointers.",
    "type": "array"
   },
+  "GenericPublicError": {
+   "properties": {
+    "body": {
+     "$ref": "#/definitions/PublicError"
+    }
+   },
+   "type": "object"
+  },
   "GettableAlertmanagers": {
    "properties": {
     "data": {
@@ -4405,6 +4413,7 @@
    "type": "object"
   },
   "alertGroup": {
+   "description": "AlertGroup alert group",
    "properties": {
     "alerts": {
      "description": "alerts",
@@ -4533,7 +4542,6 @@
    "type": "object"
   },
   "gettableAlert": {
-   "description": "GettableAlert gettable alert",
    "properties": {
     "annotations": {
      "$ref": "#/definitions/labelSet"
@@ -5641,6 +5649,12 @@
     "responses": {
      "204": {
       "description": " The mute timing was deleted successfully."
+     },
+     "409": {
+      "description": "GenericPublicError",
+      "schema": {
+       "$ref": "#/definitions/GenericPublicError"
+      }
      }
     },
     "summary": "Delete a mute timing.",

pkg/services/ngalert/api/tooling/definitions/provisioning_mute_timings.go

@@ -63,6 +63,7 @@ import (
 //
 //     Responses:
 //       204: description: The mute timing was deleted successfully.
+//       409: GenericPublicError
 
 // swagger:route
 

pkg/services/ngalert/api/tooling/definitions/shared.go

@@ -20,3 +20,10 @@ type ForbiddenError struct {
 	// in: body
 	Body errutil.PublicError `json:"body"`
 }
+
+// swagger:model
+type GenericPublicError struct {
+	// The response message
+	// in: body
+	Body errutil.PublicError `json:"body"`
+}

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

@@ -1281,6 +1281,14 @@
    "title": "Frames is a slice of Frame pointers.",
    "type": "array"
   },
+  "GenericPublicError": {
+   "properties": {
+    "body": {
+     "$ref": "#/definitions/PublicError"
+    }
+   },
+   "type": "object"
+  },
   "GettableAlertmanagers": {
    "properties": {
     "data": {
@@ -4590,13 +4598,13 @@
    "type": "object"
   },
   "gettableAlerts": {
+   "description": "GettableAlerts gettable alerts",
    "items": {
     "$ref": "#/definitions/gettableAlert"
    },
    "type": "array"
   },
   "gettableSilence": {
-   "description": "GettableSilence gettable silence",
    "properties": {
     "comment": {
      "description": "comment",
@@ -7624,6 +7632,12 @@
     "responses": {
      "204": {
       "description": " The mute timing was deleted successfully."
+     },
+     "409": {
+      "description": "GenericPublicError",
+      "schema": {
+       "$ref": "#/definitions/GenericPublicError"
+      }
      }
     },
     "summary": "Delete a mute timing.",

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

@@ -2785,6 +2785,12 @@
         "responses": {
           "204": {
             "description": " The mute timing was deleted successfully."
+          },
+          "409": {
+            "description": "GenericPublicError",
+            "schema": {
+              "$ref": "#/definitions/GenericPublicError"
+            }
           }
         }
       }
@@ -4688,6 +4694,14 @@
         "$ref": "#/definitions/Frame"
       }
     },
+    "GenericPublicError": {
+      "type": "object",
+      "properties": {
+        "body": {
+          "$ref": "#/definitions/PublicError"
+        }
+      }
+    },
     "GettableAlertmanagers": {
       "type": "object",
       "properties": {
@@ -8001,6 +8015,7 @@
       "$ref": "#/definitions/gettableAlert"
     },
     "gettableAlerts": {
+      "description": "GettableAlerts gettable alerts",
       "type": "array",
       "items": {
         "$ref": "#/definitions/gettableAlert"
@@ -8008,7 +8023,6 @@
       "$ref": "#/definitions/gettableAlerts"
     },
     "gettableSilence": {
-      "description": "GettableSilence gettable silence",
       "type": "object",
       "required": [
         "comment",