add a new codec to avoid sdk imports in modules

core/codec/codec.go

@@ -0,0 +1,22 @@
+package codec
+
+import "cosmossdk.io/core/transaction"
+
+// Codec defines a Binary Codec and JSON Codec for modules to encode and decode data
+type Codec interface {
+	BinaryCodec
+	JSONCodec
+}
+
+// BinaryCodec defines a binary encoding and decoding interface for modules to encode and decode data
+// The Binary Codec uses protobuf
+type BinaryCodec interface {
+	Marshal(transaction.Msg) ([]byte, error)
+	Unmarshal([]byte, transaction.Msg) error
+}
+
+// JSONCodec defines a JSON encoding and decoding interface for modules to encode and decode data
+type JSONCodec interface {
+	MarshalJSON(transaction.Msg) ([]byte, error)
+	UnmarshalJSON([]byte, transaction.Msg) error
+}