Alerting: Get grafana-managed alert rule by UID (#86845)

* Add auth checks and test

* Check user is authorized to view rule and add tests

* Change naming

* Update Swagger params

* Update auth test and swagger gen

* Update swagger gen

* Change response to GettableExtendedRuleNode

* openapi3-gen

* Update tests with refactors models pkg

pkg/services/ngalert/api/tooling/definitions/cortex-ruler.go

@@ -8,6 +8,18 @@ import (
 	"github.com/prometheus/common/model"
 )
 
+// swagger:route Get /ruler/grafana/api/v1/rule/{RuleUID} ruler RouteGetRuleByUID
+//
+// Get rule by UID
+//
+//     Produces:
+//     - application/json
+//
+//     Responses:
+//       202: GettableExtendedRuleNode
+//       403: ForbiddenError
+//       404: description: Not found.
+
 // swagger:route Get /ruler/grafana/api/v1/rules ruler RouteGetGrafanaRulesConfig
 //
 // List rule groups
@@ -206,6 +218,12 @@ type PathGetRulesParams struct {
 	PanelID int64
 }
 
+// swagger:parameters RouteGetRuleByUID
+type PathGetRuleByUIDParams struct {
+	// in: path
+	RuleUID string
+}
+
 // swagger:model
 type RuleGroupConfigResponse struct {
 	GettableRuleGroupConfig