Arizona Supreme Court held that (1) under Arizona Rule of Civil Procedure 4(i), if a plaintiff shows good cause for failing to serve a defendant within ninety days, a court is required to extend the time for service; (2) Rule 4(i) also allows a court, in its discretion, to extend the period for service without a plaintiff showing good cause; and (3) that if the ninety-day period for service has expired, a plaintiff seeking an extension under Rule 4(i) need not show that the delay in service or