* `cloud::legacy` talks to Cloud API V1.
* `cloud::api` defines Cloud API v2.
* `cloud::local` mocks the Cloud API V2 using a local postgres instance.
* It's possible to choose between API versions using the `--api-version` flag.
* [proxy] Add SCRAM auth
* [proxy] Implement some tests for SCRAM
* Refactoring + test fixes
* Hide SCRAM mechanism behind `#[cfg(test)]`
Currently we only use it in tests, so we hide all relevant
module behind `#[cfg(test)]` to prevent "unused item" warnings.