feat: pause code completions

[Le0X8]

I would like to have a feature like in VS Code that turns completions off for a few minutes, which get enabled back again after a set period of time.

VS Code uses a timer for this, there's a button called "Pause code completions for 5 minutes" and after it's pressed, you either have the option to add 5 minutes on top or cancel the timer completely. After the timer reached 0 seconds, completions get turned back on.

I would love to have this feature in Zed, as sometimes I need to do coding tasks for university, and I just turn them off to keep it fair.