Add unit tests for Kafka dissector (#807)

* Add unit tests for Kafka dissector

* Return `io.EOF` if request or response header size is zero

* Sort the slice in `representMapAsTable`

* Remove the dead code

* Remove more dead code

* Remove more dead code

* Fix `dissector.Analyze` call

Co-authored-by: gadotroee <55343099+gadotroee@users.noreply.github.com>

tap/extensions/kafka/structs.go

@@ -12,19 +12,6 @@ const (
 	RequireAll  RequiredAcks = -1
 )
 
-func (acks RequiredAcks) String() string {
-	switch acks {
-	case RequireNone:
-		return "none"
-	case RequireOne:
-		return "one"
-	case RequireAll:
-		return "all"
-	default:
-		return "unknown"
-	}
-}
-
 type UUID struct {
 	TimeLow          int32 `json:"timeLow"`
 	TimeMid          int16 `json:"timeMid"`