Bring back UI for execution

[zoeyTM]

fixes #259

[zoeyTM]

Added a VerboseEventHandler

[alcuadrado]

Great progress! Good idea to start with the verbose logging listener.

Now that we decided to have independent ExecutionEvents that don't necessarily map 1:1 with JournalMessages, I think we can apply this simplification: Instead of having the deployment loader emit the ExecutionEvents, emit them directly whenever needed.

I think this would mean emitting them in:

• Deployer._getOrInitializeDeploymentState when a new deployment gets started.
• Deployer.deploy, to emit the BATCH_INITIALIZE event.
• Maybe in the execution engine to emit an event when each batch started (maybe I missed this event)
• All the places where applyNewMessage is called, except maybe in the Wiper.

Also, how annoying is it to have to use this weird syntax?

public [ExecutionEventType.RUN_START](event: RunStartEvent): void {
// ....
}

[zoeyTM]

@alcuadrado ah okay, i can update that!

As for the weird syntax, we don't technically have to do it that way. We could also do

public RUN_START(event: RunStartEvent): void {
// ....
}

I just did it the current way because I figured it was one less thing we have to update if we ever change one of the enum values but maybe I'm overthinking it. Now that I'm typing this out, though, I'm thinking there's not really a reason besides convention that we couldn't do something like:

export enum ExecutionEventType {
  RUN_START = "runStart",
  WIPE_EXECUTION_STATE = "wipeExecutionStart",
  // etc...
}

which would make the handler functions just normal function names. Thoughts?