Align faces when only bounding boxes are provided

The BoundingBoxAnnotatorCrop cropper uses a 2 stage strategy to crop and align faces in case annotation_type has a bounding-box. In the first stage, it crops the face using the {topleft, bottomright} parameters and expands them using a margin factor. In the second stage, it uses the annotator to estimate {leye and reye} to make the crop using :py:class:bob.ip.base.FaceEyesNorm. In case the annotator doesn't work, it returns the cropped face using the bounding-box coordinates.

It's being a while that I wanted to put this in place.

Follow the impact of this on the test1 IJB-C protocol (old 1:1) and on the test4 protocols (open-set identification protocols)

test1.pdf dir-test4-g1.pdf dir-test4-g2.pdf

Do you have sometime to review this one @lcolbois ?

Thanks