Use GUID_DEVCLASS_COMPUTEACCELERATOR for NPU discovery (#24660)
### Description
Updated device discovery to use `GUID_DEVCLASS_COMPUTEACCELERATOR`
instead of `GUID_DEVCLASS_SYSTEM` when querying SetupAPI for potential
NPU devices. This provides a more specific and accurate class for
identifying compute accelerators like NPUs.
This change also saves us an average of 5 milliseconds by not looping
through unnecessary system devices.
### Motivation and Context
When looking for NPUs, the previous code used `GUID_DEVCLASS_SYSTEM` as
the class to query for potential devices and didn't return the Qualcomm
NPU.