Fixes for dim bounds and touch bounds

- Change dimming and touch related usage to use task's "max visible
  bounds", which is the app within a task that's covering the maximum
  visible area looking down from top. This solves the problem where
  an app pops up a dialog window. We should dimming (and allow touch)
  the entire task area, not just the dialog's visible area.

- Fix initial bounds used in drag moving/resizing, this should be
  visible bounds of the app main window, not the original task bounds.

- Fix touch region set up for freeform apps, even when task is not
  full screen, we should get the max visible bounds first (as freeform
  app could have dialogs too).

bug: 25494928
bug: 25487005
bug: 25613403

Change-Id: Ib1c6a1665fb83ded2fcb0a7ea92cf1def5372edd