feat: unify events under one source

[weboko]

This is a feature request

Problem

Right now we have different event sources such as:

• libp2p;
• connection manager or other js-waku code parts;

Later, when we want to action on something like network state change - we need to have a dependency on the emitting source which in this case is connection manager.

At the same time we have libp2p as a source of some other events.

All of the mentioned events are useful event outside of js-waku code base and can be leveraged by app developers.

Proposed Solutions

Unify libp2p and js-waku specific events under one source.
Make it accessible throughout code base so that we can emit or listen to events everywhere.
Expose such event source to outside.

As temporary means we can leverage libp2p for emitting and listening to events.
For outside it is better to expose something like node.events.addEventListener.

Notes:

• Example - d17cd91