Add to gateway the ability to onboard a new ICS user

[shannonwells]

Summary

Endpoint for posting the 3 necessary ICS payloads for onboarding, which will be posted to chain immediately, via a new ICS queue, using payWithCapacityBatchAll.

Context

This is to support Access Control Lists.

Outline or additional Details

[PM/Eng]: Acceptance criteria

• New endpoint in account-api that takes a new public key and a schema ID
• The schema is validated and the job is pushed to the account-worker
• The worker executes the transaction using the Provider keys.
• Unit and e2e tests for same
• Swagger docs updated
• MDBook updated
• Updates to documentation are reviewed by Jeanette and/or Diego

[shannonwells]

This needs some fleshing out by someone who is more familiar w/ graph-api

[JoeCap08055]

I think this should be in account-service rather than graph-service, as keys are a general concept not limited to Graph.
Also, need to clarify some points:

• Current Graph key schema is marked SignatureRequired, which means it does not honor a Delegation, but instead requires a signed payload by the key owner. I'd assume any additional encryption key schemas would implement the same flag. This needs to be accounted for in the endpoint design; account-service already has some similar endpoints, I believe.

[shannonwells]

Meeting notes:

• separate endpoints for each itemized schema update
• new HCP controller
• specific endpoints for queueing individual context fragments to be batched? Yes
• do we need accessor/retrieval endpoints for storage retrieval thru gateway? Maybe, ask team
• separate story: stand up a new HCP service and it encapsulates all you need for HCP endpoints, it builds its own docker image and that is what gets deployed. doesn't need a separate api and worker service.