Add Spectral rules to validate that interfaces are defined on the specific node referenced (169)

[willosborne]

Addresses #169

Adds a new rule; technically this overlaps with the 'not defined anywhere' rule which I could probably cut.
But 'not defined anywhere' and 'not defined on the right node' are different data points in my mind.
Could merge them into one, what do people think?

[willosborne]

Would be good to get input from @Thels here before I merge - I needed to npm install rollup for the spectral CI job to work, and I also needed to add link to the dev dependencies to prevent an error in the CI jobs. Not sure how that was merged in - I was seeing the issues on CI too so not just my machine.

RE the CI jobs, I think we should probably just replace the Spectral CI job with running the CLI directly anyway - make things more consistent and use our own tools.

[Thels]

Spent time with @willosborne to understand why we needed to package install link package but the use-case he encountered was completely valid.

As discussed we do need to consider updating all of the node versions used in the GH actions soon as they're out of sync with the project itself.