Add TestHTTPOption for gateway-api

[nak3]

knative networking repo added a new test as knative/networking#415.

And 0.4.0-rc1 should support this filter kubernetes-sigs/gateway-api@e4536a0

[github-actions]

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[ReToCode]

To summarise, this issue could be done with the current gateway-api spec, but it is a bit verbose (see the PR: #437).
So before we merge it, we are waiting to see what kubernetes-sigs/gateway-api#1185 will bring for version 0.7.0 of the spec (#437 (comment)).

[dprotaso]

Just an FYI - I tried to see if there was interest in simplifying this upstream.

I didn't get the votes kubernetes-sigs/gateway-api#3103 (comment) so it's not going to be in 1.2 (Sept). So the earliest it could land now if it was part of 1.3 would be next year.

I'm thinking we go ahead with the verbose approach