REST API for public key management

[trevex]

Once a user logged in via the CLI. They should be able to manage public keys.

An authenticated user should be able to:

• list their own public keys
• upload a new public key
• delete one of their public keys

The API should be implemented as REST API (gRPC as alternative debatable as well).
The API should be a self-contained package which can add routes to an existing gin engine and allows the drop-in of an
arbitrary auth route protecting function.