windows replace uni with cmd to start up main window after installation (#8235)

This is to avoid uni link not working

Other change: The install window now has the title "appname - Install" to distinguish it from the main application window.

Signed-off-by: 21pages <pages21@163.com>

flutter/lib/main.dart

@@ -338,7 +338,6 @@ void runInstallPage() async {
     windowManager.focus();
     windowManager.setOpacity(1);
     windowManager.setAlignment(Alignment.center); // ensure
-    windowManager.setTitle(getWindowName());
   });
 }