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/authorization_test.go

@@ -49,7 +49,7 @@ func TestAuthorize(t *testing.T) {
 		}
 		paths[p] = methods
 	}
-	require.Len(t, paths, 44)
+	require.Len(t, paths, 45)
 
 	ac := acmock.New()
 	api := &API{AccessControl: ac}