Build rules to derive greylists from annotations.

Uses the new class2greylist tool to extract API descriptors from .class
files.

Also add these generated greylist.txt files as dependencies of
INTERNAL_PLATFORM_HIDDENAPI_LIGHT_GREYLIST so they can be merged later in
the build.

Bug: 110868826
Test: m
Change-Id: I406587732b537f9b56768ad9909039dfab34c334