message: Use abi serializer to deserialize transaction to get_required_keys so that json actions can be passed
diff: @@ -970,7 +970,11 @@ read_only::abi_bin_to_json_result read_only::abi_bin_to_json( const read_only::a
  read_only::get_required_keys_result read_only::get_required_keys( const get_required_keys_params& params )const {
  transaction pretty_input;
  - from_variant(params.transaction, pretty_input);
  + auto resolver = make_resolver(this);
  + try {
  + abi_serializer::from_variant(params.transaction, pretty_input, resolver);
  + } EOS_RETHROW_EXCEPTIONS(chain::transaction_type_exception, "Invalid transaction")
  +
  auto required_keys_set = db.get_authorization_manager().get_required_keys(pretty_input, params.available_keys);
  get_required_keys_result result;
  result.required_keys = required_keys_set;
  