appsec: collect edge waf headers

[Julio-Guerra]

What does this PR do?

Collect more HTTP headers from different WAF vendors in the request span.

System tests: DataDog/system-tests#2287

Motivation

ASM's integration with thrid-party edge WAFs (CloudFlare WAF, AWS WAF...)

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.
• Add an appropriate team label so this PR gets put in the right place for the release notes.
• Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.

For Datadog employees:

• If this PR touches code that handles credentials of any kind, such as Datadog API keys, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.

Unsure? Have a question? Request a review!

[eliottness]

I trust you to double check on the new list of headers since I don't have a link to the document referencing them.

[pr-commenter]

Benchmarks

Benchmark execution time: 2024-04-02 13:21:01

Comparing candidate commit 7416d85 in PR branch julio.guerra/appsec-edge-waf-headers with baseline commit 23b2b69 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 43 metrics, 1 unstable metrics.