feat(nlb): add eip auto selection support for nlb

[aschaber1]

Issue

This pull request introduces a new annotation, service.beta.kubernetes.io/aws-load-balancer-eip-tags, allowing users to dynamically assign Elastic IPs (EIPs) to an internet-facing Network Load Balancer (NLB) based on their AWS tags.

We don't want to hardcode certain IP allocations, and unfortunately the NLB does not support selecting IPs directly from an IPAMPool.

Description

This change adds a new annotation, service.beta.kubernetes.io/aws-load-balancer-eip-tags, that enables selecting unassociated EIPs for an internet-facing NLB by their tags instead of their specific allocation IDs. This simplifies the process for users who manage many EIPs, as they no longer need to manually find and specify individual allocation IDs.

The annotation's value is a comma-separated list of key=value pairs, which the controller uses to filter available EIPs. It finds all unassociated EIPs that match all specified tags. The controller then assigns these EIPs to the NLB, ensuring there are enough matching EIPs for the number of subnets the NLB is deployed in. This new annotation provides a more flexible way to manage and assign static IPs to NLBs.

This functionality complements the existing service.beta.kubernetes.io/aws-load-balancer-eip-allocations annotation, offering an alternative for EIP management.

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 🌟

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: aschaber1
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[linux-foundation-easycla]

• ✅login: aschaber1 / name: Alexander Schaber / (6a26823)
• ✅login: aschaber1 / name: Alexander Schaber / (6a26823, 36b6712)

The committers listed above are authorized under a signed CLA.

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