Create iCal files for message events #789
Description
In the WhatsApp app, the events have a handy button for adding events to the calendar. It could be cool if there were support for something similar for the bridged messages. A brief google search revealed some old MSCs for supporting RSVPs/calendar events but it doesn't seem like any of them ever went anywhere.
A more compatible approach could be by having the bridge send two messages for each event invite from WhatsApp: the preview text as it is now, and the event as an iCal file.