When Gitaly makes internal API calls back to Workhorse in Git hooks,
Workhorse previously would generate new correlation IDs, making it hard
to trace the entire call flow.

In https://gitlab.com/gitlab-org/labkit/-/merge_requests/123, we added
the ability to propagate correlation IDs from trusted CIDR blocks.

To use this feature, we add two configuraton parameters:

* `trusted_cidrs_for_x_forwarded_for`
* `trusted_cidrs_for_propagation`

If propagation of correlation ID is enabled,
`trusted_cidrs_for_x_forwarded_for` tells LabKit what remote IPs can be
trusted to use the `X-Forwarded-For` HTTP header to resolve the actual
client IP. Note that this parameter is not yet used in Workhorse's
remote IP resolution, but it should be.

`trusted_cidrs_for_propagation` allows Workhorse to restrict propagation
to certain IP ranges. We will want to add the Gitaly servers to this
list.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/324836

Changelog: added