Add a server to provide information about data sources and destinations

[lazamar]

The server will be served at the specified --port. Currently it has the endpoint /projections which will return info about the partition and all projection consumers.

Here is an example response

$ curl localhost:8080/projections | jq .
{
  "postgres_source": {
    "partitions": {
      "0": 40,
      "1": 43,
      "2": 50,
      "3": 55,
      "4": 30,
      "5": 44,
      "6": 31,
      "7": 40,
      "8": 34,
      "9": 66
    },
    "projections": {
      "Administration_Administration_Projection_DetailsFromAdministratorId": {
        "0": 40,
        "1": 43,
        "2": 50,
        "3": 55,
        "4": 30,
        "5": 44,
        "6": 31,
        "7": 40,
        "8": 34,
        "9": 66
      },
      "Administration_Administrator_Projection_AdministratorIdFromEmail": {
        "0": 40,
        "1": 43,
        "2": 50,
        "3": 55,
        "4": 30,
        "5": 44,
        "6": 31,
        "7": 40,
        "8": 34,
        "9": 66
      }
    }
  }
}