Add video test to check copyExternalImageToTexture scaling issues

[greggman]

I'm not sure how to describe this but I was trying to use video with WebGPU and ran into the issue that Chrome and Safari mis-scales video when using copyExternalImageToTexture with certain videos.

I didn't check if the same issue exists with importExternalTexture

There's a repo here: https://greggman.github.io/doodles/test/webgpu-video-issue/video-test-with-file.html

It loads a 1920x1080 video. In WebGPU it sets the canvas size to the size of the video and the uses copyExternalImageToTexture to copy it directly into the canvas. In Chrome, in Windows the result is wrong size. In Safari on Mac the result is also the wrong size.

In WebGL it uses texImage2D to copy the video into a texture and then renders that texture to the canvs, This works on both browsers.

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Safari, Mac

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Chrome, Windows

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Once we know what the issue is hopefully we can make a test for it