AlertingNG: POC of evaluator under feature flag. (#27922)

* New feature toggle for enabling alerting NG

* Initial commit

* Modify evaluate alert API request

* Check for unique labels in alert execution result dataframes

* Remove print statement

* Additional minor fixes/comments

* Fix lint issues

* Add API endpoint for evaluating panel queries

* Push missing renaming

* add refId for condition to API

* add refId for condition to API

* switch dashboard based eval to get method

* add from/to params to dashboard based eval

* add from/to params to  eval endpoint

Co-authored-by: kyle <kyle@grafana.com>

pkg/setting/setting.go

@@ -327,6 +327,11 @@ func (c Cfg) IsLiveEnabled() bool {
 	return c.FeatureToggles["live"]
 }
 
+// IsNgAlertEnabled returns whether the standalone alerts feature is enabled.
+func (c Cfg) IsNgAlertEnabled() bool {
+	return c.FeatureToggles["ngalert"]
+}
+
 type CommandLineArgs struct {
 	Config   string
 	HomePath string