Adds logging when:

- recursive webhook calls are detected.
- the total number of webhooks triggered by other webhooks within a
  sequence goes above a threshold.

The detection uses a header, which is passed through from the request to
the web hooks to track graphs of web hook requests.

The feature is behind a feature flag.

The next iteration will be to block the webhook from firing rather than
log.

https://gitlab.com/gitlab-org/gitlab/-/issues/329743
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/75821