[Examples Browser] Support device type switching

[ellthompson]

Adds support for graphics device type switching in the examples browser. Users can choose to run each example using WebGL 1, WebGL 2 or WebGPU.

The browser will attempt to run the current example using the selected device, however if that device is not usable for a given example a fallback device will be used instead. This will be displayed to the user as follows:

If the user selects an unsupported device type, then switches to an example which can use that device type, their selection will be restored. This allows a user to click through both WebGL and WebGPU examples while keeping track of their preferred device type.

Only examples with the following property set will support the WebGPU device type. This will allow us to progressively enable WebGPU in different examples as its support matures.

static WEBGPU_ENABLED = true;

Fixes #5027

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[mvaligursky]

Looks great, cannot wait to test this.
Left few suggestions before merging.