Tab / Mirror of traffic

Nobody has claimed this yet.

## Feature Request
We would like to have the ability to mirror traffic to one service to another url

### What problem are you trying to solve?
This would solve an issue where we want to either test a new version with production traffic or alternatively debug an issue by using production traffic

### How should the problem be solved?
Either by extending the traffic split to allow mirroring

What do you want to happen? Add any considered drawbacks.
The traffic from one service gets mirrored to another service

### Any alternatives you've considered?
We have tried to use tap but for debugging, which would solve one half of the problem.
The issue is that tap doesn't allow to see the POST request body so we can't see whats being sent in and what is responded

Is there another way to solve this problem that isn't as good a solution?

### How would users interact with this feature?

If you can, explain how users will be able to use this. Maybe some sample CLI
output?

Start by reviewing the existing traffic-split behavior and the tap approach described in the issue. Determine how mirrored requests, including POST bodies and responses, should reach another service URL without affecting the primary request. Done means the interaction and trade-offs are specified and traffic can be mirrored reliably.

Written by the indexing model from the issue text.