Replace Node EventEmitter with standard EventTarget

[pascalduez]

• goal: remove the events polyfill from our client bundles.
• Use an EventTarget which is native to both Node and browsers, but have fewer capabilities compared to EventEmitter.
• Emulate EventEmitter.listenerCount to keep the expected behaviour on errors.
• The only breaking change is that event listener will get passed data as a single event object instead of individual params.