Add bp-based disting of android stubs

This used to be done in Make, but with bp-based dist now supporting
tags we can convert these java_library { hostdex: true } libraries
to dist their classes.jar rather than dex jar.

Bug: 161214753
Test: diff results of `m sdk dist`
Change-Id: Id54507e297b5c57d1ce58f14eb347e7661a5328d