Update effective date for all group location network associations

Updates the effective date for ALL network associations linked to the specified group location in a single bulk operation — every network row for the location is overwritten to the same date. Use this endpoint when all associations for a location share the same effective date; to update a single specific network association instead, use PATCH /groups/locations/{locationId}/networks/{networkId}/effective-date. effectiveDate is required and must be in YYYY-MM-DD format.