turnip: image_view rework

Instead of exposing various layout functions, move image-related logic into tu_image.c and have the image_view pre-fill relevant register values.

This changes the clear/blit code to use image_view.

This will make it much easier to deal with aspect masks, in particular for planar formats and D32_S8.

Note: this replaces one of my patches in !4484 (closed) (I will rebase on this after this gets merged),