LP1086550 Not clear to patron how to deselect a facet

LP1086550 Not clear to patron how to deselect a facet

Adds an X icon in front of a selected search facet on the Bootstrap OPAC
search results screen. Hides X from screen-readers and from tab
navigation to eliminate redundant noise / effort.

Release-note: Adds an X icon to selected search facets in OPAC.

Signed-off-by: Terran McCanna <tmccanna@georgialibraries.org>
Signed-off-by: Stephanie Leary <stephanie.leary@equinoxoli.org>
Signed-off-by: Jane Sandberg <sandbergja@gmail.com>
Signed-off-by: blake <blake@mobiusconsortium.org>