[camera_web] Update ultra high resolution to 4096x2160

[bselwe]

Updates ultra high resolution from 3840x2160 to 4096x2160 to the web camera platform. Fixes an issue when requesting the maximum camera resolution resulted in a 640x480 camera, rather than 1280x720.

Part of flutter/flutter#45297.

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• I listed at least one issue that this PR fixes in the description above.
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[bselwe]

@ditman

[ditman]

Let's go with this one, but I have a feeling that these presets are going to be quickly surpassed by the capabilities of the hardware :/