message: rpc: Treat all args after a hidden arg as hidden as well
  This commit has no effect right now, but hardens the code for the future
diff: @@ -504,7 +504,7 @@ std::string RPCHelpMan::ToString() const
  ret += m_name;
  bool was_optional{false};
  for (const auto& arg : m_args) {
  - if (arg.m_hidden) continue;
  + if (arg.m_hidden) break; // Any arg that follows is also hidden
  const bool optional = arg.IsOptional();
  ret += " ";
  if (optional) {
  @@ -526,7 +526,7 @@ std::string RPCHelpMan::ToString() const
  Sections sections;
  for (size_t i{0}; i < m_args.size(); ++i) {
  const auto& arg = m_args.at(i);
  - if (arg.m_hidden) continue;
  + if (arg.m_hidden) break; // Any arg that follows is also hidden
  if (i == 0) ret += "\nArguments:\n";
  