Default VTL formula for max Date is using wrong functions

In Pogues, we can define a range for a Date type response domain. If the designer don't, some default values are used.

In this case, the DDI will be:

```xml

1900-01-01
format-date(current-date(),'[Y0001]-[M01]-[D01]')

```

Note that the VTL expression in the maximum value is using the functions `format-date` and `current-date` which are valid XPath functions but not valid VTL functions (there is a `current_date` in VTL but not a `format_date`).

Ideally, we should if possible replicate the existing mecanism (using the current date).

The target is probably to be able to give both dates and VTL formulas in the Pogues fields.