add th attribute data-sort-reverse

[zevero]

I needed to have different sort order for columns
Honoring the global option descending:true and avoiding any asc, desc logic I just added the attribute data-sort-reverse.

[tristen]

👋 @zevero thanks for the PR. I'm curious why aria-sort isn't enough and why a data-sort-reverse attribute is necessary.

[zevero]

Thanks for your quick response @tristen !
I tried aria-sort on my column and yes it seemed to work initially. But when sorting another column in between aria-sort ends up beeing cleared and from now on that column will be sorted contrary as expected.
So thats why I introduced an everlasting data-sort-reverse ;-)