[Go] Object API support (#5339)

* start

* works for current usages!

* unpack: vector of struct

* optimize byte slice

* support nested struct

* support null table

* support struct

* support union

* update generated code

* grumble

* fix compiler warning

* update generated code

* wrap type in namespace

* bug

* wrap in namespace

* enum byte arrays

* generate struct for unions

* basic testing

* remove branching

* fix assert

* pack vector of fixed structs correctly

* omit null vectors

* Refactor Union Pack and UnPack methods

Remove append usage to increase code efficiency when dealing with large vectors

* generate goldens

tests/MyGame/Example/Stat.go

@@ -6,6 +6,31 @@ import (
 	flatbuffers "github.com/google/flatbuffers/go"
 )
 
+type StatT struct {
+	Id string
+	Val int64
+	Count uint16
+}
+
+func StatPack(builder *flatbuffers.Builder, t *StatT) flatbuffers.UOffsetT {
+	if t == nil { return 0 }
+	idOffset := builder.CreateString(t.Id)
+	StatStart(builder)
+	StatAddId(builder, idOffset)
+	StatAddVal(builder, t.Val)
+	StatAddCount(builder, t.Count)
+	return StatEnd(builder)
+}
+
+func (rcv *Stat) UnPack() *StatT {
+	if rcv == nil { return nil }
+	t := &StatT{}
+	t.Id = string(rcv.Id())
+	t.Val = rcv.Val()
+	t.Count = rcv.Count()
+	return t
+}
+
 type Stat struct {
 	_tab flatbuffers.Table
 }