Reference: #7723

The existing traffic direction configuration provides two options: ingress and egress.
For Envoy deployed as a middle or an edge proxy, there is no guideline for setting this option.
The option affects the behavior of the tracing engine (e.g. whether to open or close a span).
Edge/middle (which are sometimes combined) may perform at least two distinct actions in the context of distributed tracing:

• be transparent, pass-through tracing contexts as-is;
• break the span into two, close the existing span and open a new one.

This is a request to extend the API with ability to control tracing behavior for the middle/edge proxies.

/cc @objectiser @htuch