For the driver composition reform we need nodes to record hardware
interfaces they're using. This change adds necessary fields.
The new fields will have a default value of None, which is the expected
value for nodes using classic drivers.
The new fields are not added to notifications yet, as they're not wired in.
Change-Id: Id7697de0276e9b2730ea62f9c562ed6e1d0f8a06
Partial-Bug: #1524745