Plugins: Requests validator (#30445)

* Introduce PluginRequestValidator abstraction with a NoOp implementation

* Update PluginRequestValidator abstraction to use the dsURL instead

* Inject PluginRequestValidator into the HTTPServer and validate requests going through data source proxy

* Inject PluginRequestValidator into the BackendPluginManager and validate requests going through it

* Validate requests going through QueryMetrics & QueryMetricsV2

* Validate BackendPluginManager health requests

* Fix backend plugins manager tests

* Validate requests going through alerting service

* Fix tests

* fix tests

* goimports

Co-authored-by: Leonard Gram <leo@xlson.com>

pkg/extensions/main.go

@@ -10,6 +10,7 @@ import (
 	_ "github.com/gobwas/glob"
 	"github.com/grafana/grafana/pkg/registry"
 	"github.com/grafana/grafana/pkg/services/licensing"
+	"github.com/grafana/grafana/pkg/services/validations"
 	_ "github.com/grafana/loki/pkg/logproto"
 	_ "github.com/grpc-ecosystem/go-grpc-middleware"
 	_ "github.com/jung-kurt/gofpdf"
@@ -26,6 +27,7 @@ import (
 
 func init() {
 	registry.RegisterService(&licensing.OSSLicensingService{})
+	registry.RegisterService(&validations.OSSPluginRequestValidator{})
 }
 
 var IsEnterprise bool = false