Ability to use date operators in custom context fields

Describe the feature request

I would like to use custom fields with the date operators. We would like to enable/disable a feature depending o the date of creation of a user.

I see that the DateOperators are hardcoded to work only on currentTime, it would be great to be able to use custom context fields with DateOperators too.

Background

We would like to enable/disable a feature depending o the date of creation of a user.

Solution suggestions

I believe we could update the DateOperator evaluator to resolve the contextValue if there is a field attached to the constraint. I could work on a PR if you think it is reasonable