Allow UnsupportedAppUsage annotations to be in separate target

Previously, all the UnsupportedAppUsage annotations were assumed to be
in the same target as was used at runtime. e.g. frameworks,
core-libart, etc. This change allows separate targets to be specified
in the EXTRA_HIDDENAPI_JARS. It is needed to avoid maintaining local
patches for those annotations in the libcore/ojluni/src/main/java code
which comes from upstream OpenJDK.

This was tested by making and then manually checking that the generated
out/target/common/obj/PACKAGING/hiddenapi-light-greylist.txt was the
same (after sorting) before and after this change.

Test: see above
Bug: 117818301
Change-Id: Icfadbe52601371f6a4cabef106750b16f6c6d4c8