Reduce PackageInstaller Binder memory pressure.

When restoring hundreds of apps on low-DPI devices, we end up sending
icon Bitmaps inline in the response instead of splitting into ashmem
regions.  To avoid triggering TransactionTooLargeException, switch to
using ParceledListSlice under the hood.

Bug: 17926122
Change-Id: Ib4da6775e79d2fcb4aaea15f58ed998df203a5f9