Add support for `--example` to `cargo chef cook`

Nobody has claimed this yet.

I'm building some example code using:
```
FROM chef AS planner

COPY . .
RUN cargo chef prepare --recipe-path recipe.json --bin my-example

FROM chef AS builder

COPY --from=planner /app/recipe.json recipe.json
RUN cargo chef cook --release --recipe-path recipe.json

COPY . .
RUN cargo build --release -p my-example --example my-example
```

And sadly it seems the dependencies that are being compiled by the `cook` step are not the same ones as the ones used by `cargo build --example my-example`, and so it's rebuilding it all.

I've found that `cook` supports `--examples`, but it seems sometimes it's not always building all the required dependencies for my example binaries, it allows to not rebuild all the dependencies, however, only a few.

Start at the `cargo chef cook` command and compare its existing `--examples` handling with the reported `cargo build --example my-example` workflow. Trace how the recipe identifies example dependencies; done means a supported `--example` option causes `cook` to compile the dependencies needed by that example without rebuilding them afterward.

Written by the indexing model from the issue text.