- Replace usage of jQuery for the event bus in `Delegator` with
  `tiny-emitter`, which we use in various other places in the application

- Change the `element` property from a jQuery wrapper to a DOM element
  and adapt the places in `Guest` that referenced it

- Remove the `on` alias for the `subscribe` method and change existing
  users to just use `subscribe`

- Convert the one remaining use of the legacy alternative approach to
  passing configuration to `Delegator` to instead pass options in the
  `super(...)` call. This allows removing support for this from the
  `Delegator` constructor.

- Add basic tests for the `Delegator` base class