When preview is downscaled and transformation origin is not the center
of the image, this causes unexpected offset. This happened, because one
matrix combined image downscaling, so it fits into preview and user
defined scale. When origin was not center of the image, this results in
incorrect offset.
Solved by splitting 1 matrix in `sequencer_image_crop_transform_matrix`
into 2 matrices. First matrix just centers and scales image to expected
size. Second matrix performs rest of transform operations. This code is
bit easier to read as well.
Pull Request: https://projects.blender.org/blender/blender/pulls/123776
3d17217025