Spike: Gateway API support for query string matching on HTTP routes

[mflendrich]

Problem Statement

Query string matching is an extended feature of Gateway API, but if we can support it we would like to.

Acceptance Criteria

• spike the options and effort to enable query string route matching in KIC. (If the implementation is sufficiently complex, then the result of this issue should be a KEP or some other kind of design doc)

[jrsmroz]

• Kong does not support routing based on query params natively.
• Path regex can't be used, as only paths are matched, not query string.
• Router expressions does not expose query string
• We don't have a plugin that can be used. We would need to create one.

Related kong issue: Kong/kong#4919

[jrsmroz]

QueryParamMatchType does not mark the QueryParams field with Support: Extended It's a doc issue.

[randmonkey]

Now Kong gateway has supported matching HTTP query parameters in expression router: Kong/kong#11348 We can move on to this (note that we only support query param matching in Kong 3.5 and later).

[mflendrich]

This feature has been implemented in Kong (Kong/kong#11348), will be backported into 3.4.x (Kong/kong#11469) and the Gateway API conformance part will be covered by #3679.