Handle Matrix -> Discord messages over 2000 chars

[nlpn00b]

Currently when sending a message from Matrix to Discord that exceeds Discord's 2000 character limit, the message gets dropped and an error gets shown. This could either be handled by splitting the message in parts and sending separate messages, similar to https://betterdiscord.app/plugin/SplitLargeMessages, or by sending the message as a txt file, which is currently done in the Discord client.

This does sound quite difficult to implement though if features like editing and deleting messages need to work. Especially if choosing the message splitting option (and what happens in Matrix if someone in Discord reacts to split messages or opens threads?), so it is probably better to go with sending a txt file, but this also has its issues, like what happens when the message is edited to <2000 characters in Matrix, does it remain a txt file or does it get converted to a normal message in Discord? And is it even possible to keep track when the message in Discord is a txt file and the message in Matrix is normal? Also if the logged in Discord user has Nitro the character limit is increased to 4000.

I'll also work on it and see if something is possible.