Support for connectionParams for Subscriptions

[AutumnalDream]

Looking through the code and using search I didn't find any mention of the connectionParams mentioned in subscriptions-transport-ws. Is it in there and I'm not seeing it or if it's not should I attempt to add it?

[florimondmanca]

Hi! I don’t think we currently have that, indeed. Not sure what those connectionParams are — it seems they’re only referred to in the connection unit operation — but happy to review any PR to add anything we’re missing related to those. :-)