check if a Plugin is present

[oxinabox]

We have register_plugin and unregister_*_plugin
I would like a function to check if a plugin is registered.

I guess technically this is a bit race conditiony,
but it would be useful.
For example, I have a worker plugin that configures our systems logging.
before running a job i want to check if a client passed to me has had it configured and if not throw an error before i call client.submit

[jacobtomlinson]

This sounds like a great feature. Do you have any interest in opening a PR to add this?

[oxinabox]

I can, but the ETA on my doing so is long.