Create codepath for onboarding data only hotspots

[Noah Prince]

Data only hotspots do not go through the normal flow, as they do not need maker approval. They do, however, still need to have valid ecc keys where we prove they are the signer.

Flow will go something like this:

Some cli outputs a signed add gateway transaction as base64 encoded.

Assume they have a solana paper wallet with sol. Onboard that as a data only hotspot. Probably should make a separate cli for this, preferably in rust so it's easy to install