Use PackageUseInfo in DexOptimizer

Pass the PackageUseInfo directly to DexOptimizer and use it to detect if a
package is used by other apps. Move the usage checks closer to dexopt so
that they can be easily adapted when we add usage info for each of the
app's code paths separately.

This is a refactoring CLs to reduce the size and complexity of the
upcoming CLs which record the usage info for each of the application
splits.

Bug: 64124380
Test: runtest -x
services/tests/servicestests/src/com/android/server/pm/dex/*

Change-Id: I8031590cdaff81ab1792ca19baddb6cb36dc021d