Blacklight core should have a minimal component for range facets that just has a form for entering endpoint values

[barmintor]

Since Blacklight has a configuration that allows overriding the component for display of a facet, the minimal range facet behaviors from blacklight_range_limit should move into core, and the plugin should be dedicated to specifically rendering a fancier UI (with associated javascript dependencies).

[barmintor]

@cgalarza I think this is what we were talking about for the Penn/Columbia use case - the changes I made to get a minimal form rendering to work in our development app are at https://github.com/cul/ldpd-findingaids-asi/commit/73f7650e05281b06c91e3103b5245b4b00ee5836