This patch splits API and conductor services for ironic-inspector.
Previous patch utilized lock from tooz coordinator, this patch adds
a coordinator wrapper for easier usage and further introduces group
interfaces.
Each conductor service will join a predefined group to mark it's
availability, on each request, API service will query members from
the group and randomly choose on of them, create desiginated topic
and deliver request to it.
The feature is tested with the memcached, file backend of tooz.
Other backends are not fully tested but may work as well, please
refer to tooz documentation for driver compatibilities[1].
[1] https://docs.openstack.org/tooz/latest/user/compatibility.html
Story: 2001842
Task: 30376
Change-Id: I419176cd6d44d74c066db275ef008fe8bb6ef37a