Custom engineUpdate/engineDoFinal(ByteBuffer, ByteBuffer).

This makes Android Keystore's Cipher implementation use a custom
implementation of engineUpdate(ByteBuffer, ByteBuffer) and
engineDoFinal(ByteBuffer, ByteBuffer). The implementation is
explicitly designed around the fact that Android Keystore transmits
input and receives output via Binder and thus there's no need to
attempt any optimizations to avoid copying input and output.

Bug: 25863382
Change-Id: I311072891f02f5e7a283628b51b8d6058b55231c