Implement/Integrate the ping function

[daviddias]

https://github.com/libp2p/js-libp2p-ping is one of the oldest features we have developed, but unfortunately got forgotten with time. @xicombd has done some work updating it and integrating it with the libp2p builds, now with this base class, we can implement ping once and have it everywhere.

• https://github.com/libp2p/js-libp2p-ping
• Integrate libp2p-ping ipfs-inactive/js-libp2p-ipfs-nodejs#13
• Integrate libp2p-ping ipfs-inactive/js-libp2p-ipfs-browser#98

My plan is to get this done this week.

[daviddias]

• feat: add ping to the mix #48
• feat/add-ping-and-test ipfs-inactive/js-libp2p-ipfs-nodejs#42

[daviddias]

Ping is implemented throughout libp2p :)