Sharesheet - Modify header scrolling behavior

To align with UX, scroll the listview before the header when
collapsing the sharesheet to its minified state, on both flings and
drags. Fix an issue with the expansion area, whereby state is only
updated if view positions are actually updated.

Bug: 129979914
Test: Visual inspection
Change-Id: I2e32a1a3288a21bcd3ce07819f77760f10d5d929