Exp/libp2p

[greymistcube]

Leaving it as a draft for future reference.
While working on this, I have run into several problems:

• Related to dotnet-libp2p:
  • IRemotePeer.DialAsync<T>() is not properly cancellable. It is impossible to timeout with a CancellationToken.
  • The implementation of IServiceProvider uses several static variables to track services provided. Most notably, the instance of IProtocol is stored in a static HashSet<T>. A service of type T is retrieved only by its type, hence it is impossible to have several IServiceProviders for multiple ITransports for unit testing.
• Related to libplanet:
  • The whole dotnet-libp2p stack is designed to have persistent connection between separate peers. That is, to continuously have a channel open with IRemotePeer obtained via ILocalPeer.DialAsync(). The issue may be with the underlying implementation of IServiceProvider on the dotnet-libp2p side, but regardless, parallel or subsequent calls to a same peer seem very unreliable.