<!-- The PR description should answer 2 important questions: -->
### What
Update Rust to
[1.81.0](https://blog.rust-lang.org/2024/09/05/Rust-1.81.0.html).
### How
Update `rust-toolchain.yaml` and Dockerfiles
V3_GIT_ORIGIN_REV_ID: 8a1fe694caaded7a12220d2460e66009f969227a
### What
Upgrade to the latest version of Rust.
### How
I modified `rust-toolchain.toml` and ran `cargo update`.
V3_GIT_ORIGIN_REV_ID: 5fe675ee5dc568cd24de542c826ffd2d355f90ff
<!-- The PR description should answer 2 important questions: -->
### What
Upgrade to [Rust
1.80.0](https://blog.rust-lang.org/2024/07/25/Rust-1.80.0.html)
### How
Update `rust-toolchain.yaml` and Dockerfiles, fix warnings.
V3_GIT_ORIGIN_REV_ID: ba797e1aba6b9623a921734473a6b70a2a38c8b7
<!-- Thank you for submitting this PR! :) -->
## Description
Upgrade Rust, as a treat. Functional no-op.
---------
Co-authored-by: Samir Talwar <samir@functional.computer>
V3_GIT_ORIGIN_REV_ID: 1e0014049e89b8658326c8d8f652df800c415526
<!-- Thank you for submitting this PR! :) -->
## Description
I think this broke when moving folders around, realised we weren't even
building it other than in `main`, this rectifies that.
V3_GIT_ORIGIN_REV_ID: f822290f9a00159d4b1b55553f31175b697a16c1
## Description
1. I've moved the architecture information we had in `CONTRIBUTING.md`
to a separate document `docs/architecture.md` so we can evolve both
separately in the future.
2. I've introduced a couple of sub directories: `utils` and `auth`, for
supporting crates that are not the core functionality of the engine so
it is easier to find the most relevant crates.
New structure:
```
crates
├── auth
│ ├── dev-auth-webhook
│ ├── hasura-authn-core
│ ├── hasura-authn-jwt
│ └── hasura-authn-webhook
├── custom-connector
├── engine
├── lang-graphql
├── metadata-schema-generator
├── open-dds
└── utils
├── opendds-derive
├── recursion_limit_macro
└── tracing-util
```
V3_GIT_ORIGIN_REV_ID: e0e9394da2fcd911f329c48107a76f8492fa304c
Support both W3C and Zipkin B3 headers and connectors will
prefer B3 headers to extract traces because Cloud Run doesn't respect
those headers.
V3_GIT_ORIGIN_REV_ID: 1471b848e71d87420bc75b9adee60951f306c856
This injects trace context headers into requests to the auth hook,
allowing us to figure out how much time is spent here.
I added a basic tracing setup to the dev-auth-webhook, using
`tracing-util`, allowing me to verify that this works. This required
moving the Dockerfile to the root so the context contains the
`tracing-util` crate too.
I have also fixed the reference agent (by updating it), and patched our
Docker Compose files to correctly set up connectivity to Jaeger.
V3_GIT_ORIGIN_REV_ID: 2ff930bda4147d00dcc73268a814b08c8a07a359
