By Parisa Hafezi and Angus McDowall DUBAI, July 8 - Control over the Strait of Hormuz has become a "golden weapon" to Iran, for which it is willing to risk new escalations with the United States, and is a bigger priority than a nuclear programme for which it accepted decades of sanctions. So central is the issue to Iranian strategy that ships passing the Strait without Tehran's approval were fired upon this week, leading to an exchange of fire with the United States that threatens last month's i