[Feature Request] Flags in OrtThreadPoolParams to allow scheduling policy/priority inheritance for created threads

### Describe the feature request

Add flags/parameters to OrtThreadPoolParams, allowing the setup of scheduling policies (Linux) and priorities/nice (Linux, Windows).

### Describe scenario use case

We are working in a low latency environment, the parent application (Linux) is working with RT-Policies to cut latencies.
Unfortunately the pthreads are created with default settings, which significantly lowers their priority, compared to the main application.

Edit:
The threads are using the parents priority and scheduler. I did a mistake while investigating. But being able to set those parameters would be good anyway.

Start by locating OrtThreadPoolParams and the thread-creation code it controls. Compare the requested Linux and Windows scheduling and priority behavior, then clarify the flag and parameter semantics with maintainers. Done means the supported settings are implemented, documented, and covered by platform-appropriate tests.

Written by the indexing model from the issue text.