* Make all structs readonly when applicable. It should reduce amount of needless defensive copies
* Make structs with trivial boilerplate equality code record structs
* Remove unnecessary readonly modifiers from TextureCreateInfo
* Make BitMap structs readonly too
* Allow copy destination to have a different scale from source
Will result in more scaled copy destinations, but allows scaling in some games that copy textures to the output framebuffer.
* Support copying multiple levels/layers
Uses glFramebufferTextureLayer to copy multiple layers, copies levels individually (and scales the regions).
Remove CopyArrayScaled, since the backend copy handles it now.
