[WICKET-6954] implement server side heart-beat + client reconnection in case of inactivity

[reiern70]

@martin-g

I have tried to use ping-pong approach but I don't know how to implement client side reconnect using it: it seems there is no any "onping" at client side. I have added a second approach were server send some small binary message as "ping" and client side use it as heartbeat to determine server is still there. In case of "disconnection", client will try to reconnect.

There still might be quite a bit of work to do in this PR or maybe use a different approach?

[reiern70]

@martin-g many thanks for your review. I will iterate on PR ASAP