Refactor KeyGestureEventHandler out of DesktopTasksController into its
own class DesktopModeKeyGestureHandler.

Test: atest DesktopModeKeyGestureHandlerTest, DesktopTasksControllerTest
Flag: EXEMPT refactor only
Fixes: 375356887
Change-Id: I0b166080878c3b79d8b551080386cdf08010adcf
5 files changed