PackageManagerService: Implement packageParser cache in ParallelPackageParser.

We save about 2800ms of cold startup time over baseline on a marlin,
and ~1200 ms over the parallel parsing case.

                   warm     cold
		   ---------------
Baseline         : 1700ms   4300ms
Parallel         : 1400ms   2700ms
Cache            : 1000ms   1600ms
Cache & parallel : 900ms    1500ms

Note that further changes will improve the speed of cache processing.

This change also includes support for :
- a flag that been flipped in code (currently set to false).
- disabling the cache via a system property.
- wiping the cache on system upgrades.
- cache versioning.

Bug: 30792387

Test: FrameworksServicesTests
Test: manual timing

Change-Id: I281710c110af5307901dd62ce93b515287c91918