Add plugin slash command support (#7941)

* add plugin slash command support

* remove unused string

* rebase

cmd/platform/server.go

@@ -75,10 +75,10 @@ func runServer(configFileLocation string) {
 		a.LoadLicense()
 	}
 
-	a.InitPlugins(*a.Config().PluginSettings.Directory, *a.Config().PluginSettings.ClientDirectory)
+	a.InitPlugins(*a.Config().PluginSettings.Directory, *a.Config().PluginSettings.ClientDirectory, nil)
 	utils.AddConfigListener(func(prevCfg, cfg *model.Config) {
 		if *cfg.PluginSettings.Enable {
-			a.InitPlugins(*cfg.PluginSettings.Directory, *a.Config().PluginSettings.ClientDirectory)
+			a.InitPlugins(*cfg.PluginSettings.Directory, *a.Config().PluginSettings.ClientDirectory, nil)
 		} else {
 			a.ShutDownPlugins()
 		}