getLud16LinkFromLud16 static method
transform a lud16 of format name@domain.com to https://domain.com/.well-known/lnurlp/name
Implementation
static String? getLud16LinkFromLud16(String lud16) {
  var strs = lud16.split("@");
  if (strs.length < 2) {
    return null;
  }
  var username = strs[0];
  var domainname = strs[1];
  return "https://$domainname/.well-known/lnurlp/$username";
}