Required roles: broadband-r

For each planned maintenance, return its impact summary: how many of your connections it affects
broken down by SLA level (e.g. office hours, 24x7), plus an entity_counts rollup with the
impacted-connection total and the provider-entity count on the maintenance. Pass a comma-separated list
of planned-maintenance UUIDs via maintenance_uuid_in. Counts only cover connections belonging to
organisations you may access; a maintenance that affects none of your connections comes back with an
empty sla_counts mapping and connections: 0.