List active *runtime* sessions through the SDK

**Is your feature request related to a problem? Please describe.**
I'm frustrated there isn't a way to list active runtime sessions programatically.

I'm under the impression that neither `idle_runtime_session_timeout=60` nor `stop_runtime_session` are closing sessions since my memory consumption is not going to 0 - so have an API/SDK function for finding and closing these sessions would help.

**Describe the solution you'd like**
I'd like to list active runtime sessions **(not memory sessions)** through the SDK so I can kill then using `stop_runtime_session` depending on their state.

**Describe alternatives you've considered**
I've tried looking for APIs or documentation on how to have access to runtime session, but found nothing about it.

**Additional context**
Add any other context or screenshots about the feature request here.

No files or tests are named. Start with the SDK entry point for stop_runtime_session and the underlying runtime service API, then verify whether active runtime sessions can be enumerated separately from memory sessions; done means exposing that list through the SDK with state information suitable for stopping sessions.

Written by the indexing model from the issue text.