[feat: gw api] Add a utility to implement Gateway API spec to generate relevant Kubernetes objects for a Gateway

[zac-nixon]

Description

See inline comments for further details. The goal of this PR is to introduce a utility that we can call from a reconcile controller that will generate a complete resource map. This is the general flow

reconciler detects changed gateway -> reconciler invokes route utility to get complete resource picture [we are here] -> translator translate k8s objects into a common format -> deployer takes the common format and materializes the elbv2 objects based off the common format.

Checklist

• Added tests that cover your change (if possible)
• Added/modified documentation as required (such as the README.md, or the docs directory)
• Manually tested
• Made sure the title of the PR is a good description that can go into the release notes

BONUS POINTS checklist: complete for good vibes and maybe prizes?! 🤯

• Backfilled missing tests for code in same general area 🎉
• Refactored something and made the world a better place 🌟

[shraddhabang]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: shraddhabang, zac-nixon

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