Just ahead of the new iPhone’s launch event, four companies have announced cases for the impending device. STM Bags has introduced three cases, led by the Harbour ($35), a handsome-looking slider case that comes in five colors. The company also announced the one-piece Opera case ($30) and kickstand-laden Arvo shell ($40). Hard Candy Cases has introduced its ShockDrop case ($40), a boxy, ruggedized case with an included screen protector and no-slip…