识别模式创建屏幕大小的对话框，背景色为黑色。按照设计方案调整大小和效果图,添加响应槽函数

Log: 2D下触控屏的OSD提示是全屏
Bug: https://pms.uniontech.com/zentao/bug-view-48588.html
Change-Id: Ib86fbfd39ed56c23168036ede0e6e5c8ec6e11c8
Reviewed-on: http://gerrit.uniontech.com/c/dde-control-center/+/6026
Reviewed-by: <mailman@uniontech.com>
Reviewed-by: fanpengcheng <fanpengcheng@uniontech.com>
Tested-by: <mailman@uniontech.com>