Format escapes in strings
  $ refmt ./input.re
  /* Copyright (c) 2015-present, Facebook, Inc. All rights reserved. */
  
  /*
      let str = "@[.... some formatting ....@\n\010@.";
   */
  
  let str = "@[.... some formatting ....@\n\010@.";
  let str = {abcd|@[.... some formatting ....@\n\010@.|abcd};
  
  let utf8_string = "😁";
  
  let keep_representation = "\n
  \t . this should be on a new line\
     ^ this should be aligned with the .
  ";
