AAPT2: Workaround for feature splits without namespacing

Android Instant Apps in its current iteration does not use namespaces,
but due to limitations on the Android resource runtime, needs to make
it look like it does.

This is due to a bug that treats any package ID that's not 0x01 or 0x7F
as a shared library. Shared libraries require unique package names.

As a workaround, and since Android Instant Apps can not have a feature
depend on another feature, we can alter the resource package name of a
feature split just before writing it out to disk. This avoids using a
unique package name while linking, thereby avoiding namespace issues.

Bug: 68820737
Test: manual
Change-Id: Ic553ed42656436bbb949393d0248ee7bb9d37860