Ultrasound-Promoted Expedient and Green Synthesis of Diversely Functionalized 6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)(aryl)methyl)pyrimidine-2,4(1H,3H)-diones via One-Pot Multicomponent Reaction under Sulfamic Acid Catalysis at Ambient Conditions