fix: 修复关于窗口被主窗口遮挡问题

Application::initAboutDialog 执行过早，qApp->activeWindow() 指针为空，关于窗口没有父对象，与主窗口互相抢占焦点

Log: 去除 Application 构造函数中调用 initAboutDialog 操作；handleAboutAction 中，若 aboutDialog() 指针不为空则 return

spark-webapp-runtime/application.cpp

@@ -26,8 +26,6 @@ Application::Application(int &argc, char **argv)
     setProductName(DEFAULT_TITLE);
     setApplicationDisplayName(DEFAULT_TITLE);
     setApplicationLicense(" <a href='https://www.gnu.org/licenses/gpl-3.0.html'>GPLv3</a> ");
-
-    initAboutDialog();
 }
 
 void Application::handleAboutAction()
@@ -109,6 +107,5 @@ void Application::slotMainWindowClose()
 {
     if (aboutDialog()) {
         aboutDialog()->close();
-        aboutDialog()->deleteLater();
     }
 }