Saudi Arabia is taking unprecedented measures to cushion the blow of rock-bottom oil prices and the new coronavirus pandemic, as the monarchy seeks to extricate the kingdom from its worst financial predicament in decades. Oil prices have crashed since early March in part because Crown Prince Mohammed bin Salman launched an oil-price war with Russia, just as the coronavirus locked down the Saudi economy and sapped global demand for crude. Prince Mohammed, the kingdom’s day-to-day ruler, later walked back the confrontation,…