fix: fill in the Fetch{Request,Response} protocol

In order to consume zstd-compressed records the consumer needs to send
and receive version 10 FetchRequest/FetchResponses, but they need to do
so in a well-formed manner that adheres to the encoding format.

Ref: https://kafka.apache.org/protocol

Signed-off-by: Dominic Evans <[email protected]>

Author: dnwe

fetch_request.go

@@ -228,6 +228,7 @@ func (r *FetchRequest) version() int16 {
 	return r.Version
 }
 
+// FIXME: get these correct
 func (r *FetchRequest) requiredVersion() KafkaVersion {
 	switch r.Version {
 	case 0:

fetch_response.go

@@ -324,6 +324,7 @@ func (r *FetchResponse) version() int16 {
 	return r.Version
 }
 
+// FIXME: get these correct
 func (r *FetchResponse) requiredVersion() KafkaVersion {
 	switch r.Version {
 	case 0: