title: Convert varbinary to varchar with encoding in presto sql and AWS athena
body: <p>I'm using AWS Athena.</p>
  
  <p>I have a string field which holds base64 encoding of a DOMString by javascript's btoa (so, not utf-8 string but instead, 16-bit-encoded string).</p>
  
  <p>So, the string <code>Fútbol España</code> is stored as <code>Rvp0Ym9sIEVzcGHxYQ==</code> (and not <code>RsO6dGJvbCBFc3Bhw7Fh</code> which is the base64 of the utf-8 encoding)</p>
  
  <p>How can I decode this string in AWS athena (presto) SQL?
  if I use </p>
  
  <p><code>select from_utf8(from_base64('Rvp0Ym9sIEVzcGHxYQ=='))</code> </p>
  
  <p>I get <code>F�tbol Espa�a</code>... is there a from_ascii or something similar, which accepts varbinary and encoding and performs the decode?</p>