[testing] add a test for the function image_apply_homography

[carlodef]

This PR adds a test for the function common.image_apply_homography.

The test uses a synthetic image made of vertical stripes and zooms it by 0.51 (i.e. zoom out by roughly a factor 2). The expected output is what the homography binary produces right now, which is not perfect (image borders are lost), so this test could be improved in the future.