Allow explicitly specified additional annotations for hiddenapi

Adds the hiddenapi_additional_annotations to allow a library to list
the libraries that provided additional hiddenapi related annotations
for a library.

Modifies merge_csv.py so it can process multiple zip files at the same
time and uses that to merge the embedded .uau files from a module and
those it depends upon.

Bug: 180102243
Test: m droid
      Verified that hiddenapi files (both aggregated ones and for the
      individual modules) are not affected by this change.
Change-Id: I796520021c7357398a9e2a09f1029e4a578b05b3