chore: ci3 phase 1

[charlielye]

CI3 is a conceptual goal for uniting the CI flow and the dev flow as much as possible, adding more depth to the bootstrap and build scripts to be able to handle our needs.

This PR introduces all the work on CI3 so far, but still has an earthly caller shell to make sure we can minimize the number of variables that have changed at once.

There is a lot of changes in this PR.
See https://github.com/AztecProtocol/aztec-packages/pull/10711/files for a subset of the changes without yarn.lock etc noise.

The big picture:

• The CI build has been made much less stateful. ci.yml now uses the ci3
  bootstrap pattern, without fully moving off the earthly targets just
  yet.
• The S3 cache mechanism is now the main cache mechanism. Note there is
  no persistent disk now supporting the build.
  There is a global cache on S3, readable without auth, that caches them
  for 10 days. We no longer think of the build in terms of docker/buildkit
  layers but instead as chunks that have different rebuild patterns that
  match files in the monorepo.
• Moving to yarn 4.5.2.

Niceties:

• faster builds due to script improvements and distributed cache
  uploading by default
• work is more properly isolated in chunks from the above effort
• spot recovery is implemented, retrying with on-demand
• we no longer use github runners, side-stepping lots of edge-cases, and
  instead rely on our builder realizing there is no work to do / hitting a
  timeout via shutdown -P
• Docker images are no longer copied from the builder, meaning a large
  class of flake is gone.

Non-niceties:

• The earthly setup is much less granular. There is two stages that have
  their own one-layer builds. The earthly cache is fairly redundant, using
  the S3 cache for most meaningful caching. (earthly will not be used in
  ci.yml in the future)
• Some CI files are now duplicated, we will do a follow-on pass to get
  rid of earthly helpers, build-system, etc
• CI currently also downloads the CI image fresh each time, will change
• we are currently pushing images to dockerhub with no expiration,
  should move to ECR
• noir-projects currently retries once in the Earthfile as a last minute
  issue was hit, will be fixed in a follow-up
• Issues: ci3 #10775

---

WORKFLOW AFTER THIS PR:

• Run ./bootstrap.sh in root to bootstrap using the (publicly available) S3 cache, ./bootstrap.sh
  full to force a full build
• Run ./bootstrap.sh ci to test the in-progress 'full CI3' locally
• Run ./ci.sh ec2 to test the in-progress 'full CI3' on an isolated runner
• For ci2.5, use earthly +ci in root to simulate ci.yml. This shares the S3 cache. Make sure to alias earthly to scripts/earthly_local.
• Put ci3 in your cache and note the ways to interact with ci in that
  folder
• Recommended workflow, as commits are now needed to run earthly or bootstrap_ec2:

# in repo root
./ci.sh draft && git commit -am "blobs work" && git push && earthly +ci

Other useful ci.sh commands are gha-url to see the last github job associated with your branch.

• Notable commands in ./bootstrap.sh are test-kind-network, test-e2e, images-e2e
• In yarn-project to run a single e2e test now use test:e2e. test
  just runs the unit tests as per other projects.

[ludamad]

main => master :)