Option to enable envoy request or response headers separately

*Description*:
>Describe the desired behavior, what scenario it enables and how it
would be used.

I would like to be able to enable envoy request headers like `x-envoy-original-path` so that I see the original path for URL rewritten requests in traces and access logs. There is an option in CTP called `enableEnvoyHeaders` which does this. However, this also enables envoy response headers which I do not want to return to clients.

Would it be possible to have separate flags in CTP for enabling request or response headers?

[optional *Relevant Links*:]
>Any extra documentation required to understand the issue.

Previous discussion here for context: https://github.com/envoyproxy/gateway/issues/8477#issuecomment-4050988146

The issue names CTP and the existing enableEnvoyHeaders option; start by tracing where that option is defined and consumed, using the previous discussion for context. Confirm that request-header and response-header behavior can be configured independently, then verify that request headers appear in traces and access logs without exposing response headers to clients.

Written by the indexing model from the issue text.