Provide an option to skip connection verification while performing a configtest

The `—-debug --configtest` is a great feature! It would also be helpful to be able to opt out the connection verifications in the input and output sections as:
1. If there are many different hosts, inputs and outputs, it may take a long time.
2. Sometimes I would just like to verify the filter section as it is more error prone or just for developing/debugging purposes.