Palladium‐Catalyzed Intramolecular Annulation of 3‐[2‐(2‐Iodobenzylamino)aryl]‐N‐arylpropiolamides: Synthesis of 3‐[5H‐Dibenzo[b,e]azepin‐11(6H)‐ylidene]indolin‐2‐ones