Notify sysui of side swipe gestures that will show the bars transiently

- This won't be needed in T when immersive mode gestures are moved
  to SysUI (b/161689946)

Bug: 208886351
Test: atest SystemUITests
Test: In both 3button/gestural (all orientations), swipe from bar
      areas, swipe from sides show entry point only when swiping over
      bars
Change-Id: Ie8f15a5fbd3248bc86a50ffcd1fc73cd08c4e214