[RFE] Move all driver-affecting information into driver_info

[aeva black]

Even though there is a defined mechanism for drivers to expose configuration
metadata (through the ``node.driver_info`` field and its related ``validate``
method), some drivers alter their behavior based on strings within the
``node.properties['capabilities']`` nested object.

This specification describes the implementation of improvements in the handling
of driver-specific information, and node-specific information provided by
operators in order to determine service behavior.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/382015

[OpenStack Infra (hudson-openstack)]

Change abandoned by Julia Kreger (<email address hidden>) on branch: master
Review: https://review.opendev.org/382015
Reason: No revision or comment in over three years. Marking abandoned. This spec can always be resurrected if interest returns.

[Julia Kreger (juliaashleykreger)]

Over the years, we've changed what comprises a "driver". It is no longer a monolithic driver, but more a set of modules working with compatible interfaces to achieve a task. In this specific case, some models utilize other fields like a node's instance_info to facilitate a deployment, based upon existing modeling and standardization, and there has been a movement to try and create specific fields for aspects like boot_mode and secure boot, but with backwards compatibility in mind, we also can't just break existing users.

Moving forward, we should open specific items for specific issues, and proceed working them from there.