RESP endpoint cannot parse request larger than packet size

When testing RESP endpoint with redis-benchmark tool it was found that when using a value size larger than a given size (in my example it was 1960 bytes) it would cause the connection to be lost. Upon further investigation it was found the decoder would have a request of the value size for a command name. This is because the read buffer is not reset when the buffer does not complete the entire request.

We need to reset the reader index when a request isn't full parsed to prevent this.