Refactor TestImageList with FakeImage class
Refactor TestImageList with FakeImage class

Change-Id: Ia60f75f65bba4c25a0a87b570b081424f982efca
Co-Authored-By: xiexs <38ff1d6c2df0dd7254f6b99bbe6101cbcbdf2849@cn.fujitsu.com>
Implements: blueprint improve-image-unittest-framework

dtroyer/python-openstackclient,redhat-openstack/python-openstackclient,redhat-openstack/python-openstackclient,openstack/python-openstackclient,dtroyer/python-openstackclient,openstack/python-openstackclient