title: Escaping quotes in Polybase with STRING_DELIMITER
body: <p>I've got a pipe delimited flat file I want to load with Polybase. String columns are quoted with double quotes and if there are double quotes in the value, they are doubled. I believe that's a valid file format:</p>
  
  <pre><code> SizeDescription|SizeCode
   "3.5 feet"|"3.5 ft"
   "2.5 inches"|"2.5"""
  </code></pre>
  
  <p>If I don't specify STRING_DELIMITER then the quotes show up in my table I'm inserting to. If I do specify STRING_DELIMITER='"' then it works properly for the first row (3.5 ft) but fails on the second row (2.5").</p>
  
  <p>Am I doing something wrong? Or is this not supported? </p>