More APIs for encryption-aware apps.

Apps can mark manifest components as being encryption-aware, which
means they can safely be run before the credential encrypted storage
is available.

Start adding filtering logic so that we only return these components
when a user is running "with amnesia."  That is to say, only device
encrypted storage is available, so the user is running but with only
partial knowledge of its data.

To avoid calling into ActivityManager with the PackageManager lock
held, we quickly determine user state and splice the state into the
flags for later per-component evaluation.

Bug: 22358539
Change-Id: Idc56ec29f1ef04da8963e004314d7f5e47400997