Don't use ImageBitmap unless colorSpaceConversion option is supported

[lilleyse]

We were seeing some artifacts in 3D Tiles Next demos that use feature id textures on Safari desktop and mobile. Interestingly the S2 demo, which also uses feature id textures, didn't have these artifacts. After more investigation the only difference was that the first two demos had images with embedded color profiles, and the S2 demo did not.

The glTF spec requires that embedded color profiles in images are ignored since it's the material definition that determines whether images are considered sRGB or linear. The same rule extends to feature ID textures. There are two ways of ensuring that:

• if ImageBitmap is not supported then gl.pixelStorei(gl.UNPACK_COLORSPACE_CONVERSION_WEBGL, gl.NONE) should be called before the HTMLImageElement is passed to gl.texImage2D
• otherwise if ImageBitmap is supported colorSpaceConversion: "none" should be passed to createImageBitmap, since UNPACK_COLORSPACE_CONVERSION_WEBGL has no effect for ImageBitmap

Most of this was already done in #9624. The problem is that Firefox and Safari support ImageBitmap but they don't support the colorSpaceConversion option so they would always apply some sort of color correction, which really breaks feature id textures. We don't want gamma correction applied to non-color data 😄

So this PR disables ImageBitmap if the colorSpaceConversion option isn't supported. Unfortunately there's no way for the browser to tell us this, made worse by the fact that the createImageBitmap promise resolves even when a non-default colorSpaceConversion option is passed in, so the approach here is for Resource.supportsImageBitmapOptions to create an ImageBitmap from a PNG with an embedded color profile twice, once with colorSpaceConversion: "none" and again with colorSpaceConversion: "default", and check that the results are different.

Downside is that we can no longer use ImageBitmap in Firefox and Safari. But at least feature ID textures are working properly now.

Fixes #9875

[cesium-concierge]

Thanks for the pull request @lilleyse!

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Reviewers, don't forget to make sure that:

• Cesium Viewer works.
• Works in 2D/CV.

[j9liu]

@lilleyse - this looks good to me! I tested the feature-picking sandcastles in Firefox and they appear as they do in Chrome.

I forgot to skip CI for the CHANGES.md change but once that's done, I'll merge.

[lilleyse]

At the last minute I realized that getImagePixels existed, so I'm using that now.

[j9liu]

Went through the same tests and it works the same, so I'll merge now.