Is your feature request related to a problem? Please describe.
I would like the ability to make a "not equals", "not null", "not matches", or "not empty array" rule when setting up response rules in Mockoon.

Describe the solution you'd like
If you could add a checkbox / additional property to the rule to negate it, I think that would suffice

Describe alternatives you've considered
I've attempted to make complex regexes to get the equivalent, but it's cumbersome and not always effective.

Additional context
Add any other context or screenshots about the feature request here.