Bug/Improvement: Unable to embed an external form in a lesson (Platform not supported)

The user attempts to embed form code (iframe/script) using the Source Code icon (<>) in a lesson's description. The error message "Platform not supported" appears, even when using the HTML editor. It appears that the editor filters out tags not on a whitelist (YouTube, Vimeo, etc.). The user wants to be able to embed external forms (such as Google Forms, Typeform, etc.) directly into their lessons to engage their students.