One‐Pot Copper‐Catalyzed Cascade Bicyclization Strategy for Synthesis of 2‐(1H‐Indol‐1‐yl)‐4,5‐dihydrothiazoles and 2‐(1H‐Indol‐1‐yl)thiazol‐5‐yl Aryl Ketones with Molecular Oxygen as an Oxygen Source