feat: Add legacy_amino_encoding (#86)

proto/cosmos_proto/cosmos.proto

@@ -88,6 +88,17 @@ message ScalarDescriptor {
     // encoding standards and simple and clear. Currently only string and
     // bytes fields are supported for scalars.
     repeated ScalarType field_type = 3;
+
+    // legacy_amino_encoding is an optional string to describe the encoding
+    // format used by Amino. The field type is chosen to be a string so that
+    // the value can either be:
+    // - a machine-readable string, such as "base64", "bech32" or "utf8",
+    // - or a human-readable string, for instance a short specification of how
+    // a big integer would be encoded using Amino.
+    //
+    // If left empty, then the Amino encoding is expected to be the same as the
+    // Protobuf one.
+    string legacy_amino_encoding = 4;
 }
 
 enum ScalarType {