This should improve synchronizing the MainLoopWindows monitor thread
with the main loop state.
This uses the `m_ready` and `m_event` event handles to manage when the
Monitor thread continues and adds new tests to cover additional use
cases.
I believe this should fix#147291 but it is hard to ensure a race
condition is fixed without running the CI on multiple
machines/configurations.
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Co-authored-by: Pavel Labath <pavel@labath.sk>
9be7194aa5