This is likely going to be backend specific. Will be useful for implementing image resizing on the GPU, as well as for readback to specific pixel formats.

On Metal backends, this can likely just use MPSImageConversion and MPSImageScale - though we need to double check the availability.

For Vulkan, I think the blit pass itself is capable of converting pixel formats but I'm not smart enough to understand the spec for vkCmdBlitImage . If it can't do resizing, the we can create a render pass and draw the mipped texture - or do software resizing.

For OpenGL, we could probably just do sofware resizing/conversion. So we'd likely need a fallback regardless.

Needed for Texture readback APIs, as these currently bounce all of our pixel data through Skia.