Plugins: Add SDK stream handler support to plugin.Client (#41650)

* add stream handler support to plugin.Client

* nil instead of empty resp

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

* nil instead of empty resp #2

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

pkg/plugins/manager/loader/loader.go

@@ -46,7 +46,7 @@ func New(license models.Licensing, cfg *setting.Cfg, authorizer plugins.PluginLo
 		cfg:                cfg,
 		pluginFinder:       finder.New(cfg),
 		pluginInitializer:  initializer.New(cfg, license),
-		signatureValidator: signature.NewValidator(cfg, authorizer),
+		signatureValidator: signature.NewValidator(authorizer),
 		errs:               make(map[string]*plugins.SignatureError),
 	}
 }