feat: libp2p async peerstore (#4018)

Refactors interfaces and classes used by `libp2p-interfaces` to use the async peer store from libp2p/js-libp2p#1058

Fixes memory leak in libp2p, discussion in linked issue above.

BREAKING CHANGE: peerstore methods are now all async, the repo is migrated to v12

Author: achingbrain

README.md

@@ -29,10 +29,6 @@
 
 > A client library for the IPFS HTTP RPC API (`/api/v0/*`), implemented in JavaScript. This client library implements the IPFS [Core API](https://github.com/ipfs/js-ipfs/tree/master/docs/core-api) enabling applications to change between an embedded js-ipfs node and any remote IPFS node without having to change the code. In addition, this client library implements a set of utility functions.
 
-## Lead Maintainer <!-- omit in toc -->
-
-[Alex Potsides](http://github.com/achingbrain)
-
 ## Table of Contents <!-- omit in toc -->
 
 - [Getting Started](#getting-started)