Support for `is_date_after` operator

[osangenis]

Feature flags using dates are failing to evaluate locally because the operator is_date_after is not known in the method matchProperty. When you use that operator, there is log entry: Unable to compute flag locally (flag_name) - Can't determine if feature flag is enabled or not with given properties --> but in reality, the issue is the operator (unknown). Then, there is a fallback to remote evaluation. I don't see a reason why it can't be computed locally.

Additionally, it would be nice to log these errors with Debug as there is a fallback to remote evaluation.

Thank you so much in advance!!!