Cache app enumeration per-package enabled state

This change queries PlatformCompat for state on package add and when the
state is changed (notified via listener) to avoid expensive
transformation to ApplicationInfo and any performance impact
PlatformCompat may itself have.

Bug: 149768323
Test: atest PackageManagerPerfTests AppEnumerationTests
Change-Id: I19d8d0918ca6d0563e86a0c84e07cb2c0202543f