[golang] Add support for text parsing with json struct tags (#7353)

* [golang] Add support for text parsing with json struct tags

Add struct tags to Go native structs generated when object API is used.

This allows to use the same JSON file as for C++ text
parsing(i.e. snake_case vs CamelCase) and thus enabling text parsing
for Go(when using object API).

* [golang] Add test for text parsing

Added small test to check and demonstrate text parsing in Go.
Also, ran clang-format on cpp file changes.

tests/optional_scalars/ScalarStuff.go

@@ -7,42 +7,42 @@ import (
 )
 
 type ScalarStuffT struct {
-	JustI8 int8
-	MaybeI8 *int8
-	DefaultI8 int8
-	JustU8 byte
-	MaybeU8 *byte
-	DefaultU8 byte
-	JustI16 int16
-	MaybeI16 *int16
-	DefaultI16 int16
-	JustU16 uint16
-	MaybeU16 *uint16
-	DefaultU16 uint16
-	JustI32 int32
-	MaybeI32 *int32
-	DefaultI32 int32
-	JustU32 uint32
-	MaybeU32 *uint32
-	DefaultU32 uint32
-	JustI64 int64
-	MaybeI64 *int64
-	DefaultI64 int64
-	JustU64 uint64
-	MaybeU64 *uint64
-	DefaultU64 uint64
-	JustF32 float32
-	MaybeF32 *float32
-	DefaultF32 float32
-	JustF64 float64
-	MaybeF64 *float64
-	DefaultF64 float64
-	JustBool bool
-	MaybeBool *bool
-	DefaultBool bool
-	JustEnum OptionalByte
-	MaybeEnum *OptionalByte
-	DefaultEnum OptionalByte
+	JustI8 int8 `json:"just_i8"`
+	MaybeI8 *int8 `json:"maybe_i8"`
+	DefaultI8 int8 `json:"default_i8"`
+	JustU8 byte `json:"just_u8"`
+	MaybeU8 *byte `json:"maybe_u8"`
+	DefaultU8 byte `json:"default_u8"`
+	JustI16 int16 `json:"just_i16"`
+	MaybeI16 *int16 `json:"maybe_i16"`
+	DefaultI16 int16 `json:"default_i16"`
+	JustU16 uint16 `json:"just_u16"`
+	MaybeU16 *uint16 `json:"maybe_u16"`
+	DefaultU16 uint16 `json:"default_u16"`
+	JustI32 int32 `json:"just_i32"`
+	MaybeI32 *int32 `json:"maybe_i32"`
+	DefaultI32 int32 `json:"default_i32"`
+	JustU32 uint32 `json:"just_u32"`
+	MaybeU32 *uint32 `json:"maybe_u32"`
+	DefaultU32 uint32 `json:"default_u32"`
+	JustI64 int64 `json:"just_i64"`
+	MaybeI64 *int64 `json:"maybe_i64"`
+	DefaultI64 int64 `json:"default_i64"`
+	JustU64 uint64 `json:"just_u64"`
+	MaybeU64 *uint64 `json:"maybe_u64"`
+	DefaultU64 uint64 `json:"default_u64"`
+	JustF32 float32 `json:"just_f32"`
+	MaybeF32 *float32 `json:"maybe_f32"`
+	DefaultF32 float32 `json:"default_f32"`
+	JustF64 float64 `json:"just_f64"`
+	MaybeF64 *float64 `json:"maybe_f64"`
+	DefaultF64 float64 `json:"default_f64"`
+	JustBool bool `json:"just_bool"`
+	MaybeBool *bool `json:"maybe_bool"`
+	DefaultBool bool `json:"default_bool"`
+	JustEnum OptionalByte `json:"just_enum"`
+	MaybeEnum *OptionalByte `json:"maybe_enum"`
+	DefaultEnum OptionalByte `json:"default_enum"`
 }
 
 func (t *ScalarStuffT) Pack(builder *flatbuffers.Builder) flatbuffers.UOffsetT {