Put base APK when AppSet is included in APEX

This change fixes a bug that base APK of an AppSet is not put into the
APEX.

Bug: 236299724
Bug: 254192829
Bug: 240449675
Test: m nothing

Merged-In: I1010ec66d8551fcc1e2d9119be7ecdba22186607
Change-Id: I1010ec66d8551fcc1e2d9119be7ecdba22186607
(cherry picked from commit 4169a25f)