Make photo taking more automatic

The manual fiddling with sliders is what keeps me away from taking more photos. There's several things across the stack but I couldn't find a tracker bug to link those together from a user's PoV so here we go. To do away with the sliders we'd need:

• Auto whitebalance (AWB) (libcamera#3)
• Auto focus (AF)
• Auto exposure (AE)

Then

• Auto flash (needs flash support in the led driver linux#351 (closed), #37)

@sebastian.krzyszkowiak post has more details and also post processing steps.

This is mostly to have a catch all issue for progress / needed things. @dorota.czaplejewicz if you think we should move this to libcamera repo feel free to just do so.