Lens IOP: fix 2 issues

First one is for those rare cases when lens is non-rectilienar (fisheye), we would not only fix distortions, but also convert geometry to rectilinear [#8493](http://www.darktable.org/redmine/issues/8493)

And second one is for lens auto-detection for fixed-lens cameras. Such images contains no info about lens in EXIF, but we can reliably detect such cases due to LenFun, and set correct lens automatically [#9028](http://www.darktable.org/redmine/issues/9028)

Note that [#9028](http://www.darktable.org/redmine/issues/9028) is a feature request, however the fix is pretty straight-forward and robust, and without it, ALL images from fixed-lens cameras require manual lens selection - takes a lot of time.
So IMO it should be merged, even now that we are in feature freeze.