Reduce multiple places to listen for events into one single place

[jankapunkt]

We can currently attach event listeners to multiple places:

• Data
  • Data.on
  • Data.onChange (attaches multiples listeners under the hood)
• Data.ddp
• Data.ddp.socket
• Db

Some events bubble through these structures as they come from levels deeper. The question is: is this too complicated? Can we abstract this into once event target which we can listen on from the outside? Does this even make sense?

On the contrary: we will have to rewrite lots of things to async/await to be isomorphic with Meteor 3, so there might be even some events that will be deprecated soon.

We should collect them as well in order to prepare the works on this.

Edit: there are also internal direct usages of EventEmitter vs. Data.notify which is a mixed design that easily leads to confusion. We should move towards a unified solution that keeps being comprehensible