AAPT2: Allow output artifacts to be filtered.

A new optional flag has been added to allow a list of artifacts that
should be written as output to be provided. If the flag is provided,
only artifacts that have an output name matching an entry in the list
will be processed.

Test: manually ran against an APK with multiple artifacts in the
configuration and confirmed that only the specified artifacts were
written.
Test: Ran all unit tests.

Change-Id: Ia32b19acf1b2ef3711abf13df08dc7b1aa0cf161