Add Virtual A/B with vendor ramdisk product.

If vendor_ramdisk exists, it is preferred to use launch_with_vendor_ramdisk.mk
because it moves e2fsck to vendor_ramdisk, making ramdisk smaller.

Devices that uses VABC is assumed to have a vendor ramdisk, so inherit
from this new makefile.

Test: pass
Change-Id: If6adad9985ca4750225fd4263edb42de1ddaf486