Add v2 version to go module name

Replace all elements from `v2` to root directory.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

object/json.go

@@ -0,0 +1,78 @@
+package object
+
+import (
+	object "github.com/nspcc-dev/neofs-api-go/v2/object/grpc"
+	"github.com/nspcc-dev/neofs-api-go/v2/rpc/message"
+)
+
+func (h *ShortHeader) MarshalJSON() ([]byte, error) {
+	return message.MarshalJSON(h)
+}
+
+func (h *ShortHeader) UnmarshalJSON(data []byte) error {
+	return message.UnmarshalJSON(h, data, new(object.ShortHeader))
+}
+
+func (a *Attribute) MarshalJSON() ([]byte, error) {
+	return message.MarshalJSON(a)
+}
+
+func (a *Attribute) UnmarshalJSON(data []byte) error {
+	return message.UnmarshalJSON(a, data, new(object.Header_Attribute))
+}
+
+func (h *SplitHeader) MarshalJSON() ([]byte, error) {
+	return message.MarshalJSON(h)
+}
+
+func (h *SplitHeader) UnmarshalJSON(data []byte) error {
+	return message.UnmarshalJSON(h, data, new(object.Header_Split))
+}
+
+func (h *Header) MarshalJSON() ([]byte, error) {
+	return message.MarshalJSON(h)
+}
+
+func (h *Header) UnmarshalJSON(data []byte) error {
+	return message.UnmarshalJSON(h, data, new(object.Header))
+}
+
+func (h *HeaderWithSignature) MarshalJSON() ([]byte, error) {
+	return message.MarshalJSON(h)
+}
+
+func (h *HeaderWithSignature) UnmarshalJSON(data []byte) error {
+	return message.UnmarshalJSON(h, data, new(object.HeaderWithSignature))
+}
+
+func (o *Object) MarshalJSON() ([]byte, error) {
+	return message.MarshalJSON(o)
+}
+
+func (o *Object) UnmarshalJSON(data []byte) error {
+	return message.UnmarshalJSON(o, data, new(object.Object))
+}
+
+func (s *SplitInfo) MarshalJSON() ([]byte, error) {
+	return message.MarshalJSON(s)
+}
+
+func (s *SplitInfo) UnmarshalJSON(data []byte) error {
+	return message.UnmarshalJSON(s, data, new(object.SplitInfo))
+}
+
+func (f *SearchFilter) MarshalJSON() ([]byte, error) {
+	return message.MarshalJSON(f)
+}
+
+func (f *SearchFilter) UnmarshalJSON(data []byte) error {
+	return message.UnmarshalJSON(f, data, new(object.SearchRequest_Body_Filter))
+}
+
+func (r *Range) MarshalJSON() ([]byte, error) {
+	return message.MarshalJSON(r)
+}
+
+func (r *Range) UnmarshalJSON(data []byte) error {
+	return message.UnmarshalJSON(r, data, new(object.Range))
+}