onnxruntime

[WebGPU EP] allows GPUDevice to be released after use (#23144)

### Description

This change allows the `WebGpuContext` class to be released after all
active inference sessions are released. This will cause:
- for default context (ID=0), the underlying `wgpu::Device` and
`wgpu::Adapter` to be released, together with all resources created by
the Device.
- for custom context (ID>0), the reference counts of passed in Instance,
Adapter and Device will decrement correctly.