Alerting: Rule backtesting with experimental UI (#115525)

* add function to convert StateTransition to LokiEntry
* add QueryResultBuilder
* update backtesting to produce result similar to historian
* make shouldRecord public
* filter out noop transitions
* add experimental front-end
* add new fields
* move conversion of api model to AlertRule to validation
* add extra labels
* calculate tick timestamp using the same logic as in scheduler
* implement correct logic of calculating first evaluation timestamp
* add uid, group and folder uid they are needed for jitter strategy

* add JitterOffsetInDuration and JitterStrategy.String()

* add config `backtesting_max_evaluations` to [unified_alerting] (not documented for now)

* remove obsolete tests

* elevate permisisons for backtesting endpoint
* move backtesting to separate dir

pkg/services/ngalert/api/authorization.go

@@ -81,9 +81,15 @@ func (api *API) authorize(method, path string) web.Handler {
 		// additional authorization is done in the request handler
 		eval = ac.EvalPermission(ac.ActionAlertingRuleRead)
 	// Grafana Rules Testing Paths
-	case http.MethodPost + "/api/v1/rule/backtest":
+	case http.MethodPost + "/api/v1/rule/backtest": // TODO (yuri) this should be protected by dedicated permission
 		// additional authorization is done in the request handler
-		eval = ac.EvalPermission(ac.ActionAlertingRuleRead)
+		eval = ac.EvalAll(
+			ac.EvalPermission(ac.ActionAlertingRuleRead),
+			ac.EvalAny(
+				ac.EvalPermission(ac.ActionAlertingRuleUpdate),
+				ac.EvalPermission(ac.ActionAlertingRuleCreate),
+			),
+		)
 	case http.MethodPost + "/api/v1/eval":
 		// additional authorization is done in the request handler
 		eval = ac.EvalPermission(ac.ActionAlertingRuleRead)