Fully detach unused scrap views

This CL fixes a bug in list view where an unused
scrap view would stay in temporarily detached
state until it is re-used.
It is an invalid state for a view and to fix
that issue, I've changed AbsListView to fully
detached scrap views at the end of a layout
pass and also treat them as regular new views once
they are re-used after being fully detached.

Bug: 28672259
Change-Id: I6e3f4da29f8cbca32787862402f5c21f674a7145