feat(plugins): major improvement in plugins golang code

pkg/plugins/panel_plugin.go

@@ -0,0 +1,19 @@
+package plugins
+
+import "encoding/json"
+
+type PanelPlugin struct {
+	FrontendPluginBase
+}
+
+func (p *PanelPlugin) Load(decoder *json.Decoder, pluginDir string) error {
+	if err := decoder.Decode(&p); err != nil {
+		return err
+	}
+
+	p.PluginDir = pluginDir
+	p.initFrontendPlugin()
+	Panels[p.Id] = p
+
+	return nil
+}