fix(network, DHT): stricter typing for event listeners in interfaces

[juslesan]

Summary

Stricter listener typing for events in the ITransport and Layer1Node interfaces.

It is no longer possible to set a listener with an inproper listener function for example: layer1Node.on('manualRejoinRequired', (peerDescriptor: PeerDescriptor) => {}) will now be caught by the compiler.

Changes

• DhtNode no longer export an Events type. It now only exports a DhtNodeEvents type that includes DhtNode and ITransport specific events.