Windows 10 build 18946

Windows 10 build 18946 is the private build of the "20H1" update for Windows 10. It was released to insiders accidentally on 2019-07-24 to Windows Insiders in the Fast ring. Also it's the first leaked build of rs_xbox_dev branch.

New features
Both features can be enabled using mach2.
 * Fully redesigned Start Menu. It is likely intended to be used in new Windows Lite operating system. Currently it works properly only wiht Lite theme.
 * New Control Center. Now it's more compact. By default it only shows buttons, but it expands as you receive notifications.