Support for GW API URLRewrite filter in HTTPRoute

[czeslavo]

Is there an existing issue for this?

• I have searched the existing issues

Does this enhancement require public documentation?

• I have added an Acceptance Criteria item for adding and/or adjusting public documentation (if applicable)

Problem Statement

As there's demand for RewriteURI feature on HTTPRoute (we've got a community pull request that implements that using an annotation as Ingress does), we should consider implementing the Gateway API's HTTPURLRewriteFilter to satisfy it.

Proposed Solution

Implement support for HTTPURLRewriteFilter using request-transformer KongPlugin attached to a route (similarly to the Ingress konghq.com/rewrite annotation implementation).

Acceptance Criteria

• HTTPURLRewriteFilter for HTTPRoute is implemented according to the Gateway API spec
• HTTPRouteRewriteHost and HTTPRouteRewritePath Gateway API conformance tests pass
  • experimental conformance - HTTPRouteHostRewrite #3685
  • experimental conformance - HTTPRoutePathRewrite #3686
• docs.konghq.com docs are updated to reflect the fact that the rewriting URL feature for HTTPRoute is implemented in other way than for Ingress (a filter vs. an annotation)
  • https://docs.konghq.com/kubernetes-ingress-controller/latest/guides/requests/rewrite-host/#rewrite-using-regular-expressions guide is updated
  • https://docs.konghq.com/kubernetes-ingress-controller/latest/guides/requests/rewrite-annotation/ guide is updated

[pmalek]

ReplaceFullPath for URLRewrite has been implemented in #5855.