refactor app protocol, add support for app protocols that kubernetes + elb supports

[zac-nixon]

Issue

#4497

Description

Per the issue, they were trying to use kubernetes.io/h2c to set the protocol version to HTTP2 on the constructed target group. Digging a bit, I had started working on supporting Service AppProtocol but left it half done (and the half that was done was incorrect :/)

This change adds support for the kubernetes.io/h2c AppProtocol (converting to HTTP2 on the TG). It also..

1. Adds guard rails so we don't attempt to set protocol version on listeners that don't support it. Credit to @starlightromero for noticing this edgecase.
2. Removed some incorrect AppProtocol validations, I was incorrectly using http and grpc as AppProtocol values.

In the future, I'd like to set up LBC specific protocol versions as per the AppProtocol spec: https://kubernetes.io/docs/concepts/services-networking/service/#application-protocol but in the meantime, I'd like to get minimal support working while removing the obviously incorrect AppProtocol references in our code.

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]

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

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