title: TypeORM sql dialect agnostic query with query builder
body: <p>Can I write the following query using TypeORM QueryBuilder to get a SQL Dialect agnostic query?</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>select *
  from mytable
  where mycol1 = 'foo'
  and mycol2 = (select max(mycol2)
                    from mytable
                    where mycol1 = 'foo');</code></pre>
  </div>
  </div>
  </p>