Create tool to analyse large monorepos and give Gitaly specification recommendations

A ongoing challenge we see our customers having is around Large Monorepos and how to spec Gitaly accordingly to handle them.

As we know Git repos can vary widely in size across different layers (blobs, trees, etc...) that makes it very difficult to give general guidelines like we do currently in the Reference Architectures. Repositories can be considered unique in this regard and how much resources Git / Gitaly requires to handle them isn't known until you try the real thing.

To help address this issue if there was a tool that performed analysis on Git repos, like a combination of Git Sizer and PGTune, that was able to give out adjusted Gitaly node spec guidance (CPU, Memory) this could be significantly helpful for these customers to right size their environments for their specific repos along with any guidance to address any bad health areas in the repo.