Enforce app updatability in GenerateAndroidBuildActions

Remove part of the apex top down mutator by moving enforceAppUpdatability
to a check in GenerateAndroidBuildActions instead of mutating
dependencies.  This requires annotating app dependencies of updatable
apexes with `updatable: true` in the Android.bp files.

Bug: 367784740
Test: builds
Flag: EXEMPT refactor
Change-Id: I234a457bba48c0f48410d53740aaa9b89661ca7c