Enabling facet field pagination component to accept other styles for the numerical sort and A-Z buttons

[hudajkhan]

Within a facet's list of values, clicking on "more" will open up a modal with various sorting options, including numerical and A-Z. The styling for the Numerical sort and A-Z buttons includes classes that are defined in the HTML for the FacetFieldPaginationComponent.

See: https://github.com/projectblacklight/blacklight/blob/main/app/components/blacklight/facet_field_pagination_component.html.erb#L13 .

For our downstream app, we need to use our own styling for the component. One method would be to build in support within Blacklight itself by allowing someone to override _facet_pagination.html.erb and pass in their own classes for these buttons.