Auto merge of #3901 - BenWiederhake:all-kinds, r=alexcrichton

Auto merge of #3901 - BenWiederhake:all-kinds, r=alexcrichton

Implementation and CLI-support for `--all-$KIND` flags

This implements #3112.

This means all of the following commands are now possible and meaningful:
```
cargo build --all-bins
cargo build --all-tests
cargo test --all-tests
cargo test --all-bins
cargo check --all-bins --all-examples --all-tests --all-benches
```

The commits try to represent the incremental "propagation" of the new feature:
- core functionality (`cargo check --lib` passes)
- CLI suport (`cargo build` passes)
- additional tests (`cargo test` covers new functionality)

Note that `--all` is already reserved to mean "all packages of the workspace", so it can't be used to mean `--all-bins --all-examples --all-tests --all-benches`.

I intend to follow this up by some other PRs, so please do tell me where I could improve.