Required roles: broadband-r

Return the doc count for each named view of the planned maintenances impacting this connection,
in a single org-scoped request. Each name matches the view values accepted by
GET /mixed-broadband/connections/{uuid}/maintenance/?view=<name>, so each count agrees with what
that view would paginate over. Pass query to restrict the counts to the same free-text search the
list endpoint accepts. A connection with no impacting maintenances reports 0 for every view.