Add custom classes at yadcf-filter-wrapper-inner level

[dwasyl]

Currently, users can use style_class to add css classes to the input object, however, it is not possible to add any custom classes to the wrapper divs. This especially applies to multi-widget filters (such as the date range picker). These objects have both a standard wrapper and an yadcf-filter-wrapper-inner object. Styling multi-widget filters often takes additional steps such that adding additional classes at the wrapper level is necessary.

Could there be an option to add custom css classes to either the yadcf-filter-wrapper-inner level or one of the more generic wrapper levels? (as then the option would apply to all filter types).

[vedmack]

@dwasyl why not style the existing classes such as yadcf-filter-wrapper-inner? the style_class support was added because of some third-party libraries that needed their own class to be present on inputs