refact: ApplicationService ctor and some member functions

Signed-off-by: ComixHe <heyuming@deepin.org>

apps/dde-application-manager/src/main.cpp

@@ -44,5 +44,5 @@ int main(int argc, char *argv[])
         return false;  // means to apply this function to the rest of the files
     });
 
-    return app.exec();
+    return QCoreApplication::exec();
 }