Update window header spec

1) Remove app name when app is using custom headers
2) Adjust padding/margins to support hiding the app name
3) Add empty drag zone on right-aligned bounding rect
4) Update close button vector, size and padding
5) Update app chip app icon size to 24x24dp

Bug: 316387515
Test: enable/disable APPEARANCE_TRANSPARENT_CAPTION_BAR_BACKGROUND flag
and observe window header UI updating to allow more custom space and a
drag-only area.

Change-Id: Ic27b98861521dbcf1253ff7618e8e773bb763988