PING PONG

[kappsegla]

To test out our connection

We can send a PING with an optional message to our server to verify that we have a working connection, that the server response isn't an error and can also be used for measuring latency.
Could also be a good smoke test to run to verify that we can produce and run a working server? Create separate issue for this.

When client sends a ping without a message
PING\r\n

the server should reply with a simple string
+PONG\r\n

If a message is included the response should be a bulk string.
PING hello\r\n
"$5\r\nhello\r\n"