Implement image capture (both synchronous and asynchronous variants)

Closes https://bugs.freedesktop.org/show_bug.cgi?id=60445
Add upektc_img driver

This one handles 147e:2020 devices which can be found in newer Lenovo laptops
imgdev: perform 5 scans for enrollment

This feature dramatically improves matching rate on devices with small
sensors.

This commit also introduces new on-disk format - FP2, older library versions
can't read that format. FP1 format is still supported. Following tests were performed:
* old libfprint + FP1 format -- works properly (old scheme)
* old libfprint + FP2 format -- fingerprint is rejects as non-compatible
* new libfprint + FP1 format -- works properly
* new libfprint + FP2 format -- works properly
build: fix autoreconf warnings
aes1660: don't lower bz2_threshold

With recent changes it's not necessary anymore, match rate is good.
vfs301: don't touch nr_enroll_stages

It's already initialized by upper layer
vfs101: don't touch nr_enroll_stages

It's already initialized by upper layer