boards: shields: Add product photos to some shields

The photos are from
https://learn.adafruit.com/assets/13421
https://learn.adafruit.com/assets/31967
https://learn.adafruit.com/assets/9187


and have the license CC BY-SA 3.0

I have cropped the photos, downsampled to width 500 px and
converted to webp.

Signed-off-by: Jonas Berg <jonas.s.t.berg@gmail.com>