Some cargo build/test tasks are not running in CI

[RobertJacobsonCDC]

A few subtle Cargo behaviors mean that we don't run what we think we run in CI:

• It turns out that if you have a "main package" in a workspace (which we do), then commands like cargo build and cargo test apply to the main package, not all workspace members.
• cargo build only builds the "default" targets lib and bin. It doesn't build test, example, and bench targets unless you also pass the --all-targets flag.
• cargo test --examples does not actually run the examples. It only runs the tests defined in the examples.

As I recall, the last one is intentional. The issue is that there is no Cargo command to run all examples automatically. There is a bit of bash code involving jq that can gather all example names and run them, but in our case one of the examples intentionally requires a command line argument, and instead of dealing with the complexity we decided at the time that it was enough just to build the examples and run their tests. Here's a complete list of commands to run all examples:

cargo run --example basic
cargo run --example basic-infection
cargo run --example births-deaths
cargo run --example load-people
cargo run --example network-hhmodel
cargo run --example parameter-loading
cargo run --example random
cargo run --example reports
cargo run --example reports-multi-threaded
cargo run --example runner
cargo run --example time-varying-infection -- examples/time-varying-infection/input.json

[RobertJacobsonCDC]

We should also build an test the web api feature, which is disabled by default. We should have something like:

cargo test --no-default-features --features "web_api logging"