Jared Kushner and Steve Witkoff were expected to land in Doha on Tuesday. DOHA, June 30 (Reuters) - Top U.S. envoys were due to arrive in Qatar on Tuesday, but uncertainty over the timing and content of any diplomatic talks raised questions over efforts to bring a lasting halt to the Iran war and fully reopen the Strait of Hormuz. The diplomacy follows exchanges of fire over the weekend that tested the June 17 interim accord between the United States and Iran. The 14-point pact allowed 60 days