Accessibility: add missing labels to gallery thumbnail size controls #1488
Description
The slider control to adjust thumbnail size in the gallery lacks labels. These should be added, in an appropriately i18n-friendly way.
See IIIF-Commons/iiif-gallery-component#1 for work-in-progress -- this was not completed before the gallery component was reintegrated into the main UV application, so we should modernize and finish it now.