add idle runner

[saleweaver]

Hey,

this may be a bit of an unusual requirement, but I need to run a check whenever the queue gets polled but doesn’t have messages in it.

I’m not sure if you want to allow for this, I’m happy to work it out to be more stable/nicer.

Let me know - thanks!

[jegesh]

Hi! Thanks for contributing! While I have no issue supporting this additional functionality, please add a commit to update the readme before I merge. Thanks again