create a eventhub workbench component

[andy-berry-dev]

Create a workbench component that can view, and possibly create, events via the event emitter

• Log channel subscriptions
• Log event bindings on channels
• Log events being triggered on channels
• Allow events to be triggered on channels from the Workbench Tool

[andy-berry-dev]

@leggetter this is the card for the EventHub workbench component if you're going to have a look at it.

[andy-berry-dev]

this is being looked at by @leggetter as part of brjs-todo work - https://pbs.twimg.com/media/BhRKoGcCEAETrV6.png:large