Use "inversion of control" pattern for HTTP proxies, OIDC

[ethnt]

Let services provide the information for their own HTTP proxies and OIDC information. For example, for Netbox:

{ config, hosts, ... }: {
  services.netbox = { enable = true; };

  provides.services.netbox = {
    name = "Netbox";
    http = {
      host = hosts.matrix;
      port = config.services.netbox.port;
      proxy = {
        enable = true;
        domain = "netbox.e10.camp";
      };
    };

    oidc = {
      client_id = "...";
      scopes = [ "" ];
    };
  };
}

Then within consumers of these (i.e., bastion), look through every host for this configuration (filtering as need be — monitor will only take from the monitor host, etc).