Remove AndroidPackageWrite

Moves all system state out of AndroidPackage and into
PackageStateUnserialized, which lives inside a PackageSetting.

This makes AndroidPackage effectively immutable after it exits
the scan/install process.

Specifically, moves isUpdatedSystemApp, isHiddenUntilInstalled,
seInfoOverride, cpuAbiOverride, PackageUsage,
and sharedLibraryFiles/Infos.

Bug: 135203078

Test: atest com.android.server.pm.parsing

Change-Id: I44baab113f3b6b138472b15a61e0874173bc694f