Explorer: do not announce 'unknown' when opening quick link menu and selecting items from it (Windows+X) (#8138)
* Explorer: do not announce 'unknown' when opening quick link menu (Windows+X). Re #8137.
Windows with the class name of LauncherTipWnd and ApplicationManager_DesktopShellWindow fires focus events, causing NVDA to announce 'unknown' when opening quick link menu (Windows+X) and selecting an item from this menu. Suppress this if possible.
* Explorer: clarify comments. Re #8137.