Extend `camera.capture()` to support zoom

[siliconwitch]

camera.capture(zoom=1.0) to camera.capture(zoom=16.0)

[josuah]

This requires quite a lot of driver tinkering: there is an arbitrary cropping feature, but the image output is not stable at any resizing level, and there is a scaling feature with fixed amount of zooming.

Maybe with the extra datasheet it can work a bit better.