Ensure resource consistency across backends

[thatcosmonaut]

We should have a test like:

// update texture, not cycled
SDL_GpuUploadToTexture(myCopyPass, myTexture, ...)

// draw call
...
SDL_GpuBindFragmentSamplers(myRenderPass, myTexture, ...)
SDL_GpuDrawPrimitives(myRenderPass, ...)
...

// update texture again, not cycled
SDL_GpuUploadToTexture(myCopyPass, myTexture, ...)

// draw call 
...
SDL_GpuBindFragmentSamplers(myRenderPass, myTexture, ...)
SDL_GpuDrawPrimitives(myRenderPass, ...)
...

The expected behavior is that each draw call should use the data that was uploaded to the texture right before the draw call. It's not good practice to do this, but it should at least behave consistently.