Rate limit the GraphQL blame field

Jerry Setorequested to merge
618765-rate-limit-blame-api-2 into master

What does this MR do and why?

Rate limit the GraphQL blame field

Charge RepositoryBlob.blame against the same per-user-and-project and per-IP limits as the REST endpoint, once per blob resolved.

Changelog: added

References

https://gitlab.com/gitlab-org/gitlab/-/work_items/618765

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