title: Add onclick attribute to image when insertEmbed quill editor
body: <p>I have inserted one image into Quill editor user this code</p>
  
  <pre><code> const index = self._quillInstance.getSelection();
    self._quillInstance.insertEmbed(index.index, 'image', img.src);
    self._quillInstance.formatText(index.index, index.index + 1, 'height', '256px');
    self._quillInstance.formatText(index.index, index.index + 1, 'width', (256 * img.width / img.height) + 'px');
    self._quillInstance.formatText(index.index, index.index + 1, 'alt', (self._lstKeyImageBase64.length - 1).toString());
    self._quillInstance.formatText(index.index, index.index + 1, 'onclick', self.handleClickImg);
  </code></pre>
  
  <p>But the onclick attribute cannot insert to the img tag in editor container.
  How can I insert onclick event to this img was inserted to Quill?</p>