I have created type definitions for all the event names that are sent
across the different frames using various `Bridge`s. It is based on the
previous `bridge-events.js`. I broke down the events in four sections
based on the direction of the messages:

* guest -> sidebar events
* host -> sidebar events
* sidebar -> guest/s events
* sidebar -> host events

For those events that didn't have a description I added one.

This is more stringent and less verbose than the previous lookup system.