Adds types to libp2p to allow user defined services.

Removes all non-essential services to allow them to be defined
alongside any custom user versions.

This increases the modularity of libp2p as default protocols like
identify, fetch and ping will not be enabled unless specifically
allowed by the user, which also decreases the attack surface area
of libp2p applications.

BREAKING CHANGE: pubsub, dht, ping, fetch and identify have been removed - re-enable these by passing them as services

…ined-services