feat: auto load qt translations

Normally, Qt applications need to explicitly load translations by themselves,
including Qt translations. Here we take the initiative to help applications
that have loaded dtk (including plugins) load translations.

Issue: linuxdeepin/developer-center#6417

src/kernel/dguiapplicationhelper.cpp

@@ -39,6 +39,7 @@
 #include <QLockFile>
 #include <QDirIterator>
 #include <QDesktopServices>
+#include <QTimer>
 
 #ifdef Q_OS_UNIX
 #include <QDBusError>
@@ -494,7 +495,10 @@ DGuiApplicationHelper::DGuiApplicationHelper()
     : QObject(nullptr)
     , DObject(*new DGuiApplicationHelperPrivate(this))
 {
-
+    // load qt/qtbase translation for qt app which load dtk ?
+    QTimer::singleShot(0, [](){
+        DGuiApplicationHelper::loadTranslator();
+    });
 }
 
 void DGuiApplicationHelper::initialize()