c7b7e4d9d4
Fix: 402219336
Test: Turn on Talkback and make sure "Add new desk" is read out when
the AddDesktopButton is focused
Flag: com.android.window.flags.enable_multiple_desktops_frontend
Flag: com.android.window.flags.enable_multiple_desktops_backend
Change-Id: Ia500114d2ac73edabe935be1920af76b0e3d4242