Let cargo2android.py generate data properties for tests.

Some tests load data from files.  These files thus need to be copied
to the correct location on the host/device so that the tests can
access them.  This adds an option to cargo2android.py so that it can
generate these data properties.

Bug: 171710847
Test: Use for a crate.
Change-Id: I14a1ad8aca4625cc5f09807d19ffd7499fcf3689
1 file changed