Support request matching for missing parameters

[martin-tarjanyi]

Is your feature request related to a problem? Please describe. I need to create different stub responses for an endpoint based on the presence of a query parameter. I'm not able to create a matcher which would activate only when a parameter is missing.

Describe the solution you'd like Support for a matcher for absent parameters or some kind of negative matcher.

Describe alternatives you've considered I see there was a similar issue in the past (https://github.com/SpectoLabs/hoverfly/issues/889) but that's not applicable for my use case.