Invert the relationship between Rufio and Tink

[chrisdoherty4]

Currently, the Rufio Machine is referenced by Hardware objects. However, Rufio and its capabilities are very much optional and having to populate something on the Hardware object whenever we want to add capabilities seems less extensible than referencing the opposite direction.

We should investigate and implement inverting the relationship between Hardware and Rufio such that Rufio types reference what Hardware creating a solution that truly extends core Tinkerbell components and paving a path for further extensions.