Move WindowInsetsCompat to support-compat

Move WindowInsetsCompat to the compat/java directory and pull the
default method implementations into a base IMPL.
Similarly, move the OnApplyWindowInsetsListener interface to compat/java
from compat/gingerbread.
Also, add a public constructor to WindowInsetsCompat to make its
interface fully compatible with WindowInsets.

Bug: 29181287
Change-Id: Ib8ccc1e48d526f602b5dbbadf5f2f24b0ce6d456
8 files changed