Migrate SystemGesturePointerEventListener to WindowContext

Previously system context derived display context passed to
SystemGesturePointerEventListener.
After R, it threw IncorrectContextUsageViolation when initialization
because display context is not a UI context.

This CL changes to pass window context to fix the Violation.

Bug: 177650348
Test: atest WmTests
Test: atest DisplayPolicyTests#testDisplayPolicyNoCrash

Change-Id: I0d17327d8a8c14ec626c0dd9ad1a4e8529174598