Search-kit transforms don't work on aggregate fields

Feedback from user testing using new transforms

When a date field already has a field transformation on it - such as MIN(receive_date) to arrive at the first donation date of a contact after a certain date - the date is not formattable as a date(), and remains a datetime. This is difficult to work with when filtering, creating forms default values, etc. It would be helpful if we could add date transforms to date fields even if field transformations are already applied.

@colemanw I've copied the description as reported - but not sure if this will be clear to you. In this case they had a search with MAX(receive_date) as one of the fields - it's a date time field but they wanted the final form to support filtering it as a date. We don't treat MIN(dates) as dates in terms of offering search ranges and because they can't truncate them to a date only they can't use a string filter either