Unified organizations endpoint

Column to order by (filter mode only). Parameterized sorts (this endpoint only): people_concentration and people_count_growth_1y sort by the named job function's people metrics — the all-time fraction of the org's tracked people in it, and its current YoY people growth % (latest month vs. one year earlier; orgs without growth data sort last) respectively — and require order_by_job_function. job_post_concentration sorts by the all-time fraction of the org's job posts matching order_by_advanced_query, which it requires. source_data_url is omitted for all three, since the listing page cannot reproduce their ordering.