Handle special tarako categories in search (bug 998814)

https://bugzilla.mozilla.org/show_bug.cgi?id=998814

Ground work for bug 987880 (only the parts relevant to search) is also included to make things easier. A script to generate translations (almost an exact copy of what was added to fireplace one month ago) to be run before extracting new strings for translators.

For client-side API users: just continue using `/api/v1/fireplace/search/featured/` endpoint, pass `cat=tarako-lifestyle`, `cat=tarako-tools` or `cat=tarako-games` and everything should be handled for you in a transparent way. Note that no Featured Apps, Basic Collections or Operator Shelves will appear.