Support for idn/punnycode

[schochastics]

A problem in #17 is the decoding of idn/punnycode.
There are Pointers in the ada code to support that but this needs further investigation

[schochastics]

This function

ada_owned_string ada_idna_to_unicode(const char* input, size_t length) {
  std::string out = ada::idna::to_unicode(std::string_view(input, length));
  ada_owned_string owned{};
  owned.length = out.length();
  owned.data = new char[owned.length];
  memcpy((void*)owned.data, out.data(), owned.length);
  return owned;
}

[schochastics]

this should do the trick

std::string charsub(ada_string stringi){

  const char* res = stringi.data;
  size_t len = stringi.length;
  ada_owned_string stringi_new = ada_idna_to_unicode(res,len);
  res = stringi_new.data;
  len = stringi_new.length;
  return std::string(res, 0, len); 
}