This patch adds the VolumeTarget object. It handles the
volume target information which is stored in the database.
Co-Authored-By: Stephane Miller <stephane@alum.mit.edu>
Co-Authored-By: Ruby Loo <ruby.loo@intel.com>
Change-Id: I814454ec5a515080d21aad58f8d43abb49b77fb3
Partial-Bug: 1526231