egl/x11/sw & vulkan/wsi/x11: Implement partial image uploads

Continuation of !27868 (closed), the rendering artifacts have been resolved, the changes have also been implemented for vulkan WSI, and lastly I've also implemented x11 shm for the egl sw platform to increase performance even more.

Testing with weston and weston-simple-egl I see performance increases, lowering draw times from 20.8ms to 20ms.