Add basic IP rate limiting to shell endpoint

What does this MR do and why?

Describe in detail what your merge request does and why.

Adds the ability to rate limit the internal/allowed endpoint by IP. This is in addition to the user-based rate limit.

Related https://gitlab.com/gitlab-org/gitlab/-/issues/343103

Screenshots or screen recordings

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

This is very difficult to test locally because of the IP address requirement and other rate limits in place.

MR acceptance checklist

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