Sharesheet - Edge to edge support

Support edge-to-edge sharesheet to align with support for new gesture
navigation. Use top inset to prevent sharesheet from scrolling
under. Use bottom inset to give the listview space for scrolling all
items into view.

Bug: 132114008
Test: Visual inspection
Change-Id: Ie96d19f187d32d477eaf0515463d1adf335f80ce