A large, non-atomic pull request to get us back in sync

[bertybuttface]

Unfortunately this is not particularly atomic so it might be worth cherry picking it but it is fine to merge.

We've gotten a little out of sync with the changes between my fork and this one. This will bring us back in sync.

The biggest changes are:

• Access Token logs straight in, providing a Password will return an Access Token and instructions how to use.
• Encryption support now works.
• Docker uses a volume so maintains state
• Bot now replies as a thread, thread has prior context when chatting to ChatGPT.
• Prefix support enabled via !chatgpt (bot doesn't have to respond to all messages).
• Env (formerly config) overhaul, improves User / Developer experience
• Runtime settings at the ChatGPT conversation level (still WIP but fine to merge)

There are some known issues e.g. a few debug prints and TODO statements left in

This is however in a better state than the current master branch so might be worth merging straight away.

[jakecoppinger]

Amazing, thanks so much for this!