aconfig: harden dependency collection

To prevent errors, when we collect dependencies for a module, walk the
blueprint modules, and ignore blueprint and disabled modules.

This avoids errors in validateAndroidModule when a android.Module (such
as a genrule) depends on a blueprint.Module, and strict checking is
enabled.

Bug: 308625757
Test: manual

Change-Id: I11f0a0b504aa18d6d786cc91319b9d1d9497c04f