[Request]: Support the rest of the EventSource public APIs

Request:

- As a Dev, I would like the ability to add event handlers for specific events dynamically after time of connection, so that I can have other events add event listeners based off a sse response.
- As a Dev, I would like the ability to remove event handlers for specific events dynamically after time of connection, so that I can have other events remove event listeners based off a sse response.
- As a Dev, I would like the ability to dispatch events for specific events dynamically, so that I can rebroadcast event after making changes to it a sse response.

Proposal:
- Update the method to better follow the the [whatwg spec for EventSoruce ](https://html.spec.whatwg.org/multipage/server-sent-events.html#the-eventsource-interface) response.

Reasoning:
- Allow for devs to dynamically attach and detach event handlers as needed.
- Follow standards put in place in spec while expanding functionality.