feat(tracing): add http.client_ip attribute

[backjo]

Summary

As a developer troubleshooting requests using trace data, I expect my access logs to be consistent with my traces. The access logs currently record the forwarded_ip, which tells me what my client's true ip is (assuming proper setup of trusted IPs etc). This change adds a span attribute for client ip using the forwarded ip

Checklist

• The Pull Request has tests
• There's an entry in the CHANGELOG
• There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Full changelog

• [Implement ...]

Issue reference

Fix #[issue number]

[oowl]

@backjo Could you help us to fix the test? This is related to your feature. https://github.com/Kong/kong/blob/master/spec/02-integration/14-tracing/01-instrumentations_spec.lua#L138

[backjo]

@attenuation will update this PR after the earlier

@backjo Could you help us to fix the test? This is related to your feature. https://github.com/Kong/kong/blob/master/spec/02-integration/14-tracing/01-instrumentations_spec.lua#L138

Should be fixed - added test attribute to verify this new one

[StarlightIbuki]

Thanks for your contribution. The change looks good. Please add a proper changelog.

[oowl]

From https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md#http-client,

The IP address of the original client behind all proxies, if known (e.g. from X-Forwarded-For). [2]

That means:
http.client_ip is the real client IP
net.peer.ip is the proxy socket source IP.

[backjo]

Added the changelog!