Description:

Add WAF support. The implementation should focus on coraza-proxy-wasm but allow other WAF solutions in the future.

• Create a design doc for the user-facing API. See Add authn policy design with JWT only #529 (draft) as an example.
• Update xds IR.
• Update the Kube provider to reconcile the WAF Custom Resource.
• Update the resource translator to translate the WAF Custom Resource into IRs.
• Update the xds translator to translate the xds IR into xds APIs, e.g. ECDS.
• Add a user-facing doc and link into Sphinx docs, e.g. user_docs.rst.
• Others?

This issue depends on #71 and/or #24.