Add module-lib to droidstubs' supported sdk types

If the android.jar is not found in the module-lib folder, it falls back
to searching it in the system folder and then falls back on the public
folder.

This only brings the functionality, we are not yet using it.

Test: m nothing
Bug: 202023154
Change-Id: I99c9004740c8e51faf53ebc3ba2444e8164215f3