ChatGPT - Slash command improvements

[Zabuzard]

We recently added a /chatgpt slashcommand. It is now time to fine-tune it:

• limit message length to prevent people from sending a huge ass message that rips all our money (maybe 200?)
• limit usages per user to maybe once per 10 seconds (can use a Caffeine cache)
• make the message optional and if its left out, a modal will popup - allowing users to enter multi-line messages, for example including code (same limits apply)

Until this issue is implemented, the slash command has to remain locked for regular users, to prevent abuse.

[tmcdonnell2]

I can take this on. What is a Caffeine cache?
I was thinking of limiting the message length/token amount by changing the parameter in the service (right now I think its 3000?)