MITM options helpers don't compose well

[kegsay]

If you want both a callback server and to restrict an endpoint, you need to fallback to WithMITMOptions and cannot use WithSniffedEndpoint. We should make this composable.

[kegsay]

Also if you want to block requests and listen, and then just drop the blocking, you can't do this currently. You need to take away the blocking and listening then re-add the listening.

[kegsay]

With #106 this should be possible now, with some rejigging, because everything is now using the callback addon.