Add capablity to accommodate read replica config

[diorahman]

Config example:

const connection = {
  // TODO: get this from .env
  user: 'hooqapi',
  database: 'backstage',
  password: 'hooqapi-password1!',
  host: 'localhost',
  port: 5432,
  max: 10,
  idleTimeoutMillis: 1000,
}

const options = {
  client: 'pg',
  connection,
  readReplica: {
    // this should be the read replica connection settings
    connection: {
      user: 'hooqapi',
      database: 'backstage',
      password: 'hooqapi-password1!',
      host: 'localhost',
      port: 5432,
      max: 10,
      idleTimeoutMillis: 1000
    }
  }
}