[ws client]: doesn't wait for Close ACK from server during close handshake

[niklasad1]

From what I understand soketto::close doesn't
wait for CLOSE ACK from the server which causes the ACK to fail from the server-side.

That certainly explains error such as:
2022-09-07T10:18:15.621704Z ERROR jsonrpsee_server::transport::ws: WS transport error: i/o error: Transport endpoint is not connected (os error 107); terminate connection: 0 which I thought was some race-condition in soketto.

The downside is that soketto doesn't have an API to do that on the client-side AFAIU.

//cc @lexnv