Slash command string regex validation

[banocean]

Regex to validate string, it helps for example in url feilds

All too showing notification on client side, like this when you don't provide required option

[sevenc-nanashi]

I think it may crush client(ReDOS)

[BadCoder1337]

re2 by Google is the solution for ReDOS

[ImpossibleReality]

Discord already said that they wouldn't implement this (and instead would add common types that bot devs would use), plus reDos is implemented in c++, and might be a hassle to add to the discord client. I think a better solution would be something like this, even if instant client side validation would be more helpful.