Allow Closure as a valid parameter for ListView::itemViewAttributes.

[glpzzz]

          > @samdark @vjik what do you think about allowing `ListView::itemViewAttributes()` to also accept a Closure so the `li` (or other item tag) could be customized according to the specific item?

I agree with @samdark. See as example:

yii-dataview/src/GridView.php

Line 705 in 848da41

private function prepareBodyAttributes(array $attributes, DataContext $context): array

Suggest implement it in separate PR only.

Originally posted by @vjik in #210 (comment)