Previously, the private deapexer module type was treated as a prebuilt
as that was the quickest way to implement it. However, there is no
reason why it should be as there is no corresponding source module type
which it might replace.
This change removes the prebuilt support to simplify the module type in
preparation for future work. As part of that it extracts the logic for
retrieving a single path from a PrebuiltSrcsSupplier to ensure
consistent behavior.
Bug: 181267622
Test: m droid
Change-Id: I1b2bb49601c13a3fff99a0026c235eaa70d2e612
56dc66e2ea