List a glossary's term counts per language, a page at a time, from the
statistics the app keeps for the glossary: one item for each of the
glossary's languages other than its source language and any language
ignored for the glossary's resource. The app updates these statistics in
the background, so a change to the glossary's terms or translations can
take a moment to show.

Organization administrators see every language. Other users see the
languages they can view in the glossary: roles on a project linked to the
glossary, for their languages; the glossary's permission overrides limit
only editing, not viewing. Users with no role on a linked project can't
see the glossary and get 404. A filter[language] that isn't one of the
glossary's languages the user can view returns no items; a language code
that doesn't exist gets 404. No plan feature is needed. Tokens need the
get_info scope.