Implement project-specific buckets to prevent name clashes

[lukateras]

GET /v1/config and PUT /v1/config (i.e. hpos-state.json v1.config) can be used to store arbitrary data. As briefly discussed, to prevent clashes, it would be nice to have a separate sub-namespace for each consumer. I'm proposing to use a project name as a namespace, like this:

{
  "holo-nixpkgs": {
    // Contents are up to holo-nixpkgs developers 
    "sshAccess": false
  },
  "hpos-admin": {
    // Contents are up to hpos-admin developers
    "email": "sam.rose@holo.host",
    "name": "My HoloPort",
    "public_key": "z4NA8s70Wyaa2kckSQ3S3V3eIi8yLPFFdad9L0CY3iw"
  }
}

What do you think? cc @robbiecarlton @JettTech