[Feature] Ability to disable all default prompts

Hey, thanks for this great app, I love it a lot :)

A power user gets frustrated when he wants to use prompts and when opening the prompt window via `/` hundreds of prompts popup, of which he never uses any. The prompts that he added himself get hard to select and find.

Due to power users using prompts many times per day, the frustration adds up, causing the user to quit and use another client. The user would love to use the app due to its other features, but this one is so essential that it is a dealbreaker. (Also applies to me 😬)

Solution: add the ability to disable default prompts and just use the manually added ones (similar to the feature of disabling default masks). Only list the prompts that the user manually added himself. Doing this makes the app much more attractive to power users.

Thanks!