Adding Discord Bot Functionality

[ShreyBiswas]

Hi - I was looking at the bot's functions, and it seemed pretty useful. I know a few Qiskit communities using Discord, and some people (including me) would personally prefer Discord to Slack/Telegram.
So, I think it could be a good idea to add functions to allow the bot to run on Discord as well as Slack/Telegram, with similar functions.

I'm aware that this is a few years old and likely isn't in active maintenance, but I'd be happy to work on this.