I have raised a sitecore support ticket. Looks like this feature is not yet available in Sitecore. Hopefully we see this in near feature.
Response from Sitecore Support:
"I have registered a feature request for the product so it can be considered for future implementation. We will inform you when there are any updates regarding your request. You can use the approach suggested in article that you have found - Sitecore page editor - how to extend page editor item editing panel."