Alerting: Add endpoint for querying state history (#62166)

* Define endpoint and generate

* Wire up and register endpoint

* Cleanup, define authorization

* Forgot the leading slash

* Wire up query and SignedInUser

* Wire up timerange query params

* Add todo for label queries

* Drop comment

* Update path to rules subtree

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

@@ -3931,7 +3931,6 @@
    "type": "object"
   },
   "receiver": {
-   "description": "Receiver receiver",
    "properties": {
     "active": {
      "description": "active",
@@ -4885,4 +4884,4 @@
   }
  },
  "swagger": "2.0"
-}
+}