Refactor PackageParser (1/n)

The PackageParser is deprecated, but two inner classes PackageLite
and ApkLite are still used widely. To move away from PackageParser,
the first step is having alternatives of these inner classes.

Besides, some constants in the PackageParser are also used. This CL
also moves them into the individual class.

Bug: 174723245
Test: make
Change-Id: Ice151dc4daf7e342e9f77cfdae69682c1d5ba56f