title: antlr4 parentheses collide with double quote for string rules
body: <p>I have defined a String like this:
  <code>STRING_TOKEN: '"'[A-Za-z0-9]+'"';</code>
  When i use a rule such : 
      <code>LENGTH_TOKEN '( 'function' )'                                               #lengthScalarOperator</code></p>
  
  <p>e.g: length("skip")</p>
  
  <p>where function is a string, i got this error: mismatched input '("' expecting '('</p>