Support XPath Date function calls/Token calculation

Hey there,

it would be nice to do some minimal time-related calculation in a XPath constraint of a data source.

There already exists time-related tokens (https://docs.mendix.com/refguide/xpath-keywords-and-system-variables/#time-related). But with those you are limited to constraints like '[%BeginOfCurrentDay%] - 1 * [%DayLength%]'

I would like to do something like:

$currentObject/Date - '1 * [%DayLength%]'

This would save me from using a microflow as datasource, depending on the page design could result in less requests to the server.