Is your feature request related to a problem? Please describe.

It would be a nice feature if the mitm event's can be run as async functions, this will enable developers of addon's to use async methods.

Describe the solution you'd like

Make the event's async!

Describe alternatives you've considered

I've tried to schedule futures in the current running eventloop but it seems that it doesn't apply changes to the HTTP flow object.

Additional context

Would love to see async possibilities, that can make some advanced addons more efficient and extensible