Import new expand icons

Also update X close icons to be vector drawables, tinting
them to the proper colors where they are currently used.

Test:
Manually verified the following with Bullhead on M (MDA70B):
1. Dropdown icons in compact and full editors are 54% transparent
black.
2. X's next to edit text views are 38% transparent black.
3. X's in search and selection bar are still 54% transparent
black.

Bug: 30160325
Change-Id: Ice24a70f02141f641c389060c37bdc87b727b230