Disable 2 finger trackpad swiping on the status bar for shade

Based on ag/28744615. Added additional logic for discarding trackpad
motion events with 2 fingers, since the shade was treating them the same
as any motion event over the status bar.

Test: Verified with trackpad on tangorpro
Bug: 356804470
Flag: com.android.systemui.disable_shade_expands_on_trackpad_two_finger_swipe
Change-Id: Ie0658123ba19e03c6fe92decab922767e440026e