Let the widgetactions debug UI reflect the state of a focused thread

[QwertyZW]

Currently when we have a multi-threaded debugging session open, Continuing a thread and having another stopped thread get autofocused on the first thread's exit, or simply manually focusing a stopped thread, causes the widgetactions debugger UI to reflect the stale running state of the old thread instead of the stopped state of the newly focused thread, leaving no means to continue any of the stopped threads.

The commit here fixes that.

The editor and the debug viewlet appear to reflect the state of the debugger correctly.

If you require I can open an issue specific to this PR and attach a gif capture of my screen to better explain myself if that's required.

[mention-bot]

@QwertyZW, thanks for your PR! By analyzing the history of the files in this pull request, we identified @egamma and @joaomoreno to be potential reviewers.

[msftclas]

This seems like a small (but important) contribution, so no Contribution License Agreement is required at this point. We will now review your pull request.
Thanks,
Microsoft Pull Request Bot

[QwertyZW]

/cc @isidorn

[isidorn]

Thanks you for the great explanation and this PR.
Your fix is good however there seems to be an underlying issue which I should look into in the future - since the seassion state map should reflect the same stopped state. Not sure why that is not the case and why your additional check is needed.