Alerting: Add extended definition to prometheus alert rules api (#103320)

* Alerting: Add extended definition to prometheus alert rules api

This adds `isPaused` and `notificationSettings` to the paginated rules api to enable the paginated view of GMA rules.

refactor: make alert rule status and state retrieval extensible

This lets us get status from other sources than the local ruler.

* update swagger spec

* add safety checks in test

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

@@ -475,6 +475,9 @@
     "health": {
      "type": "string"
     },
+    "isPaused": {
+     "type": "boolean"
+    },
     "keepFiringFor": {
      "format": "double",
      "type": "number"
@@ -492,6 +495,9 @@
     "name": {
      "type": "string"
     },
+    "notificationSettings": {
+     "$ref": "#/definitions/AlertRuleNotificationSettings"
+    },
     "queriedDatasourceUIDs": {
      "items": {
       "type": "string"
@@ -3769,6 +3775,9 @@
     "health": {
      "type": "string"
     },
+    "isPaused": {
+     "type": "boolean"
+    },
     "labels": {
      "$ref": "#/definitions/Labels"
     },
@@ -3782,6 +3791,9 @@
     "name": {
      "type": "string"
     },
+    "notificationSettings": {
+     "$ref": "#/definitions/AlertRuleNotificationSettings"
+    },
     "query": {
      "type": "string"
     },
@@ -6649,4 +6661,4 @@
   }
  },
  "swagger": "2.0"
-}
+}