support hostname match for aigetewayroute CR

[xianml]

Hello team,
thanks for the great work of aieg! it really helps us a lot~

Currently, aigetewayroute seems act as cluster level CR, since it did not have a hostname attached to it. It means that we can not specific a group of models under a specific Hostname (say xx.api.aieg.com). And meanwhile, /v1/models will return all the openai models of all aigetewayroute CRs in the cluster.

Would you consider supporting hostname in aigetewayroute CR and derived a HTTPRoute with hostname ? If yes, i am happy to contribute on this topic

[mathetake]

yeah I think this makes sense to have them on AIGatewayRoute API