add multi-delete support for identity

This is part2. Add support for these objects:
identity.project(v2.0)
identity.role(v2.0)
identity.user(v2.0)
identity.project(v3)
identity.role(v3)
identity.user(v3)
identity.group(v3)

Closes-Bug: #1400597
Change-Id: I270434d657cf4ddc23c3aba2c704d6ef184b0dbc