Add NPU support and updating URL arguments for developer preview demos

[NingW101]

@ibelem @anssiko PTAL

[ibelem]

Thanks @NingW101 , will not merge this PR until we support these NPU demos.

[anssiko]

I'll approve this to be merged when the NPU demos are functional, but please be prepared to do another update to align with the new design once ready:

MLDeviceType was removed in PR webmachinelearning/webnn#809 and a new query mechanism is being defined in webmachinelearning/webnn#815

This suggests further changes to the urlArgs passing and other code paths that use device types is needed when that new design is finalized and reflected in the implementation.

[ibelem]

Thanks @anssiko for the reminder. Yes, we are still using MLDeviceType in demos, samples, WebNN EP of ONNX Runtime Web, will update the test framework code when we use new design.

[anssiko]

@ibelem feel free to share your use cases in webmachinelearning/webnn#815 from the test framework perspective. I understand more explicit control over device types would be very helpful for this framework. Perhaps a specific runtime flag could allow more control over device types for testing purposes.