InProcessKernelClient: Do not use run_sync if already in a running loop

[frmdstryr]

I have an application that uses an integrated Qt and asyncio event loop that embeds an ipython console using enaml's ipython console.

When the run_sync call finishes here it attempts to close the main loop causing the whole app to hang.

This just adds a check so if it's already in a running loop it just uses that instead.

[frmdstryr]

After reading through the run_sync code it looks like it might be something with async qt integration (https://github.com/codelv/asyncqtpy) not working in a nested thread.

The code was working fine with the old nest_asyncio implementation.

[blink1073]

Hi @frmdstryr, this might be fixed by #1137, I'll be releasing a bugfix early next week.

[frmdstryr]

Indeed. Thanks!