Add WebDeviceInputSystem unit tests to cover pointermove before pointerdown cases

[AmoebaChant]

These unit tests protect against regressions of the fix which addressed the bug where systems which call pointermove before pointedown got the WebDeviceInputSystem into a bad state where it would no longer accept additional touch events. See commit: https://github.com/BabylonJS/Babylon.js/commit/aa2398ea386c16739839384e7d50fb6bfe032f55

[bjsplat]

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[bjsplat]

Snapshot stored with reference name: refs/pull/15120/merge

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[bjsplat]

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[bjsplat]

Visualization tests for WebGPU (Experimental) Important - these might fail sporadically. This is an optional test.

https://babylonsnapshots.z22.web.core.windows.net/refs/pull/15120/merge/testResults/webgpuplaywright/index.html