Add test to show issues with widest stub dex jars

The widest stub dex jars should include the widest stub dex jars
provided by each module. So, if module A has public, system and test
and module B has only public then the widest stub dex jars should
include module A's test and module B's public stub dex jars. Instead,
they just include module A's test.

That behaviour is needed so that when the "hiddenapi list" tool is run
against a module C that it is passed stub dex jars from both module A
and module B so that any references to the types provided by those APIs
can be resolved.

A follow up change will fix this issue.

Bug: 179354495
Test: m nothing
Change-Id: Ibd31964e8d2a33fa92fbd0b800c9fe054ee359c7