Description
#### Problem
I connect to my own solana node via websocket, but I found It seems not provide a complete heartbeat flow (send ping then get pong).
imho, a pong not only a server response, also a network performance. I can know there is something wrong via a late response time.
#### Proposed Solution
Just like other api do, response a struct `{"jsonrpc":"2.0","result":"pong","id": 1}` or something like that.