Hide connections menu when only one connection is configured

* Make UI look cleaner for the common case of only one configuration
* Save some width to help with
  https://github.com/Martchus/syncthingtray/issues/65 a little bit

plasmoid/package/contents/ui/FullRepresentation.qml

@@ -394,6 +394,7 @@ ColumnLayout {
             paddingEnabled: true
             enforceMenuArrow: true
             onClicked: connectionConfigsMenu.toggle(x, y + height)
+            visible: plasmoid.nativeInterface.connectionConfigNames.length > 1
             Shortcut {
                 sequence: "Ctrl+Shift+C"
                 onActivated: connectionsButton.clicked()

tray/gui/traywidget.cpp

@@ -433,6 +433,7 @@ void TrayWidget::applySettings(const QString &connectionConfig)
         m_connectionsMenu->actions().at(0)->setChecked(true);
     }
     m_ui->connectionsPushButton->setText(m_selectedConnection->label);
+    m_ui->connectionsPushButton->setHidden(secondaryConnectionSettings.empty());
     const bool reconnectRequired = m_connection.applySettings(*m_selectedConnection);
 
     // apply notification settings