[TRT RTX EP] Don't register set device function when we use existing stream

[hadiFute]

Description

• Don't register set device function when we use existing stream
• Fix bug nv_execution_provider.cc : set device only if user did not provide existing stream

Motivation and Context

In some use cases, we push a user generated CUDA context, create streams using this context, and then provide these streams to TRT-RTX.
However, we noticed that after calling Run(), the custom context is replaced by another CUDA context created by ORT. This means that TRT-RTX is no longer using the original CUDA context.
After investigating further, we found that the new context is being created in onnxruntime/core/framework/stream_execution_context.cc.
The solution we propose is to not register set device function if we provide the stream.

Also there is a bug in onnxruntime\core\providers\nv_tensorrt_rtx\nv_execution_provider.cc.
We should set the device only if the user has not provided any stream. (coherent with the original comment)

[hadiFute]

@microsoft-github-policy-service agree company="NVIDIA"

[hadiFute]

For review @chilo-ms @edgchen1 @ishwar-raut1