Barretenberg in monorepo

[ludamad]

For smoother developer experience we have decided to roll https://github.com/AztecProtocol/barretenberg into the aztec monorepo (i.e. this repo).

Upsides:

• easier system discovery
• easier cross-domain releases (e.g. new system primitives like builtins, cross-system renaming, cross-system C++ style changes, API cleanup causing slight differences downstream etc)
• efficiency in cross-system (especially per-repo) tasks

Downsides:

• losing productive friction around API barrier
• not obvious where to find barretenberg
• disruptive to current workflow
• easier to move fast in a smaller repo

Planned actions:

• We can introduce a mechanism such as CODEOWNERS and a corresponding review policy as hopefully a more productive form of the disruptive friction that existed in barretenberg.
  Critical: We want barretenberg to remain something we think very consciously about modifying as it must be audited effectively. The most important part of the audit process is the dev cycle. It is important to ensure that confidence in the code by barretenberg's core devs is maintained.
• For now to keep it obvious where to find barretenberg and less disruptive short term, we're opting for repo mirroring and a https://github.com/ingydotnet/git-subrepo approach
• Feature branches if needed could disable parts of CI etc to get to a light workflow again, while still being ready to merge into master in a tactical way

Also see task list.

Original message in the experiment PR
"This has a good deal of buy-in at this point. If we want outward facing
repos, we can do it programmatically without breaking atomicity.
Our ideal mindset until closer to launch is to have everyone thinking
what brings the most value incrementing the system,
which implicitly means moves that cross the most dimensions
inherently go farther. A real and frequent example is changing a concept
on our whole stack at once, e.g a new builtin, different proving system
iteration having a different ideal interface etc."

Tasks

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1. Integrate barretenberg code and CI situated at circuits/cpp/barretenberg
2. Ensure barretenberg circuits/cpp/barretenberg is either a viable path or move it
3. Integrate release please with barretenberg as part of aztec
4. Ensure that barretenberg has a stable release path (in monorepo? keep mirroring?)
5. Consider sources of productive friction (review policy or CODEOWNERS)
6. Documentation for working on barretenberg independently or with aztec circuits
7. Documentation and tooling for working on barretenberg with noir or aztec noir contracts
8. Gather feedback on state of CI post monorepo and consider new issues
9. Gather feedback from barretenberg core devs on other post-monorepo UX

[ludamad]

Good progress on this but I'll hold off until full CI port

[ludamad]

CI has been fully ported, marking done