Attach vendor partition to cuttlefish.

This change is part of the effort to move custom (vendor) extensions to
/vendor partition.
This change complements ag/2924351 and requires vendor.img to be
available (a dummy file would currently suffice).

Change-Id: I8ac68c3820fa62cf77fe819ebfe6ed7ad96d4a8b
(cherry picked from commit 83a9cdd1b61eff26b73d4eef0c611dd1e6619063)
4 files changed