videocrop: Add Y444 support

Hey guys, I added Y444 support for the videocrop filter.

For that, I refactored the existing implementation for planar cropping to be parameterized on the used subsampling. The subsampling parameters are stored in gint subsampling[3] within the element's struct, and are initialized in gst_video_crop_set_info(), according to the pixel format.

The CI indentation failure is a bit weird. Running gst-indent locally put it in a new line. CI then wanted it back in its original line, and when moving it back to one line, CI wanted it to have go in a new line...