Avoid parceling redundant ApplicationInfo objects within PackageInfo

Two benefits:

  1) marshaling one flattened ApplicationInfo as part of a PackageInfo parcel
     rather than one per included ComponentInfo; and

  2) producing one ApplicationInfo at unmarshaling time and sharing the
     reference to it among all included ComponentInfo instances, rather
     than the previous implementation that generated a separate
     ApplicationInfo instance for each ComponentInfo.

In some cases there can be many hundreds of ComponentInfo objects embedded
in a single PackageInfo, so coalescing duplicates is a significant win
for both payload size and object pressure.

Bug 19519502
Bug 20453802

Change-Id: Ib888810dad4471084fab9ead1ebb5e0b932905f1