Plugins: Plugin Store API returns DTO model (#41340)

* toying around

* fix refs

* remove unused fields

* go further

* add context

* ensure streaming handler is set

pkg/services/provisioning/plugins/config_reader.go

@@ -1,6 +1,7 @@
 package plugins
 
 import (
+	"context"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -113,7 +114,7 @@ func (cr *configReaderImpl) validatePluginsConfig(apps []*pluginsAsConfig) error
 		}
 
 		for _, app := range apps[i].Apps {
-			if p := cr.pluginStore.Plugin(app.PluginID); p == nil {
+			if _, exists := cr.pluginStore.Plugin(context.TODO(), app.PluginID); !exists {
 				return fmt.Errorf("plugin not installed: %q", app.PluginID)
 			}
 		}