Pass HTTP client IP to WAF

[lloeki]

What does this PR do?

Pass HTTP client IP to WAF, which in turn makes it blockable.

Motivation

IP blocking.

How to test the change?

Specs, or manually:

# with Datadog.configure { |c| c.appsec.ip_denylist = ['1.2.3.4'] }
curl -vv -H 'X-Forwarded-For: 1.2.3.4' -H 'Accept: text/html' http://127.0.0.1:9292/
curl -vv -H 'X-Forwarded-For: 1.2.3.4' -H 'Accept: application/json' http://127.0.0.1:9292/
curl -vv -H 'X-Forwarded-For: 1.2.3.4' -H 'Accept: text/plain' http://127.0.0.1:9292/
curl -vv -H 'X-Forwarded-For: 1.2.3.4' http://127.0.0.1:9292/