In anticipation of Thursday’s introduction of Apple’s iPad Air 2 and iPad mini 3 — leaked today by Apple — accessory maker Designed by M has already introduced the Simple Stand ($35) for iPad Air 2 and iPad mini 3. Simple Stand holds an iPad Air 2 or iPad mini 3 in portrait or landscape position, and it includes a built-in amplifier for sound. The stand hasn’t been added to the company’s website yet, but it will be available…