<!-- 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
