[MM-57194] Allow plugins to mark setting fields as secret (#27986)

Co-authored-by: Claudio Costa <cstcld91@gmail.com>

server/channels/app/plugin.go

@@ -378,6 +378,25 @@ func (ch *Channels) ShutDownPlugins() {
 	}
 }
 
+func (a *App) getPluginManifests() ([]*model.Manifest, error) {
+	pluginsEnvironment := a.GetPluginsEnvironment()
+	if pluginsEnvironment == nil {
+		return nil, model.NewAppError("GetPluginManifests", "app.plugin.disabled.app_error", nil, "", http.StatusNotImplemented)
+	}
+
+	plugins, err := pluginsEnvironment.Available()
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to get list of available plugins")
+	}
+
+	manifests := make([]*model.Manifest, len(plugins))
+	for i := range plugins {
+		manifests[i] = plugins[i].Manifest
+	}
+
+	return manifests, nil
+}
+
 func (a *App) GetActivePluginManifests() ([]*model.Manifest, *model.AppError) {
 	pluginsEnvironment := a.GetPluginsEnvironment()
 	if pluginsEnvironment == nil {