sorting & [data-datetime-format / [data-date-format]

sorting of dates isn´t working.
Due to a naming issue:
- in the [documentation](https://www.jplist.org/documentation/controls/dropdown-sort) you want the html-attribute "data-date**time**-format"
- in your code you are [looking for the html-attribute "data-date-format"](https://github.com/1rosehip/jplist-es6/blob/2b3a53e03a6c485755bfa52c24fc02eb3d6fc60d/src/1.2.0/controls/base/controls/sort/base-sort.control.js#L45)

we´re trying to use the datesorting in a dropdown filed

The issue is in base-sort.control.js line 45, where the code looks for 'data-date-format' but the documentation says 'data-datetime-format'. Check how date sorting is initialized and used in the dropdown control. Update the attribute name in the code to match the documentation, then test sorting with a date dropdown to verify it works.

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