I remember something like this was already there, being in a lot of accessibility guidelines/requirements to have clear description setc. of where links go to. Yes there is:
But it's Plone 3-4 still (last updated 2014) and mentions a lot of tinymce. I can't figure out from the description of the add'on alone if the tinymce integration part is only putting an extra css class on the item and that the html output transforms adds filesize etc when the css class is present on the link. Or that the tinymce plugin part is doing more than that.