The Octavia API sort function was not working correctly for some
columns that have different names in the API vs the data model.
This patch also handles the case where a column may be a compound
object in the data model, such as vip_address->vip.ip_address.
Change-Id: I0c124e80fec2ac9ad813e78df6ad25da6b8e9668
Story: 2007991
Task: 40626
(cherry picked from commit b6f6c14292)