title: How to encode string to RFC 3986 in Flutter or Dart?
body: <p>I am trying to encode a string to  RFC 3986. I have found the method Uri.encodeComponent but that encodes the string to RFC 2396. 
  Basically, I am looking for an alternate method for a method in PHP i.e rawurlencode. In php this method encode the string to RFC 3986. Is there any such method in Dart or Flutter?</p>