Destroy token session

[MarhiievHE]

Currently, the token of logged-in users and sessions is stored in Maps at the Metacom level. They are indirectly accessed from endpoints via the Client class. This class contains methods to create and restore a connection but does not contain a method to close the connection or destroy the token.
Such a method would be useful since, in order to instantly lower the access level of a user who has already logged in, you must either break the connection or remove the token from his session, which is currently impossible to do from the endpoint.
I tried to implement it with the following method in the Client class:

deleteSession(token) {
    const session = sessions.get(token);
    if (!session) return false;
    const channel = channels.get(this);
    if (channel.session) {
      sessions.delete(channel.session.token);
      channel.session = null;
      return true;
    } 
    return false
  }

I'm not sure if this is the best solution, maybe you can make a better implementation or suggest something else to achieve the goal?

[georgolden]

@MarhiievHE please create PR for this. I think this feature can be added.