Feat: Pub/Sub at the service layer

[thantos]

Using #272

Move the service to service subscribe and publish behaviors to the service layer.

const serviceB: Service = service.from(...);

// put service B events into service A bus
serviceB.subscribe({ events: [] });

// subscribe directly to another service
subscription("forwardEvents", {
   service: serviceB,
   events: []
}, async () => {});

[sam-goodwin]

Not sure what you mean by service layer? Do you mean out of the cdk?