Allow autocomplete on facets with large numbers of values

[cmungall]

Ontology facets can involve large numbers of values. Our current solution of showing the most highly populated ones works most of the time, with the "More" link being a useful way to search on the rest.

But the more link can be a bit sluggish. If instead this brought up an autocomplete form, restricted to the appropriate ontology, this might be useful.

This idea should be run by users before considering implementation

[kltm]

berkeleybop/bbop-js#8