StrictMode to catch implicit Direct Boot matching.

When an app starts becoming Direct Boot aware, it can be difficult
to track down all the places they're implicitly relying on
PackageManager filtering behavior.

For example, if the current Launcher isn't Direct Boot aware, we
hide it until the user is unlocked, which could confuse other Direct
Boot aware apps into thinking it had been uninstalled, which could
cause data loss.

This change helps apps track down places where they're implicitly
relying on the automatic filtering; they should instead carefully
choose a combination of MATCH_DIRECT_BOOT flags to decide on the
explicit matching behavior they want.

To implement this, we partially migrate the updateFlags() methods
out into ApplicationPackageManager, since the checking needs to
happen on the client side to correctly report StrictMode
violations.  We don't currently mutate the flags, but we retain
the naming to keep that door open in the future.

Test: manual
Bug: 110413274
Change-Id: Iff6feba19da81ea1b4eeb3af821c3bdfbd9bf17c