only eth_subscribe newPendingTransactions on the backend when a user is subscribed on the frontend

[BlinkyStitt]

this was a firehose so I turned it off, but there are some people that want it.

[BlinkyStitt]

config can turn this on again, but its a lot of data sent even when no one is subscribed to.

• need to make it so we only subscribe to the backends if someone is susbcribed on the frontend