first pass at creating filtering terms from katsu public config

[gsfk]

First pass at creating beacon filtering terms from katsu public config (Redmine #1578, #2193)

• Needed to (eventually) drive beacon UI from beacon backend; currently the UI still calls katsu on its own, with beacon left not knowing about its own filter options.
• Helpful for beacon network
• uses "values" list proposed for beacon spec, although can be used even if not adopted.

May need tweaks for use with scoped discovery config.