This change introduces a new module ironic.drivers.hardware_types
with AbstractHardwareType class. It also updates driver_factory
code to support loading hardware types and creating dynamic drivers.
Interfaces validation code extended to cover hardware types.
This change also introduces the FakeHardware class for testing.
It is special-cased to bypass compatibility validation completely.
No hardware types are loaded on conductor start up yet, as hardware
types still do not participate in the hash ring. Thus, nodes with
hardware types cannot still be created via HTTP API.
Change-Id: If8e3342baf818a9e37aa82b43aec71898d48c29b
Partial-Bug: #1524745
901171194b