De-dupe http matches

[kate-osborn]

trafficstars

When creating certain configurations such as multiple listeners with no hostnames, and having an httproute bind to all listeners, it can result in duplicate http matching configs. While this result doesn't cause any issues, it results in nginx and our njs module doing extra work that they don't need to be doing.

We should ensure that we de-duplicate our http matches before updating nginx.

Example: https://github.com/nginxinc/nginx-kubernetes-gateway/pull/885#issuecomment-1644581979