List every geography at one boundary level, for one country ('ireland' or 'united-kingdom'). level defaults to "county" (Ireland's 26 counties); the UK's own primary level is "lad" (local authority districts), not "county". Other levels exist per country (e.g. Ireland's "local_authority", "garda_division") -- see a dataset's own compatible_levels from query_data for which levels a given stat is actually published at. Returns each area's id (used by query_data's area-scoped modes, always paired with the SAME country) and name.