Traverse workspace members (each with their own binaries and examples)

[rnag]

Is your feature request related to a problem? Please describe.

Let's use this project as an example:
https://github.com/sonos/tract

Support Binaries in src/bin

I try to run cargo run at root level, I get following output:

$ cargo run
error: `cargo run` could not determine which binary to run. Use the `--bin` option to specify a binary, or the `default-run` manifest key.
available binaries: example-dump-nnef-mobilenet-v2, example-nnef-mobilenet-v2, example-onnx-mobilenet-v2, example-pytorch-resnet, example-tensorflow-mobilenet-v2, jupyter-keras-tract-tf1, jupyter-keras-tract-tf2, pytorch-albert-v2, reset-test-list, tract

Hmm - that's strange! Where did all those binaries come from? It's really interesting, because those are not ones defined at root level either. Looks like those are binaries/examples of workspace members actually.

Take this binary target: reset-test-list

It looks like that is actually coming from a workspace member, harness/onnx-test-suite > src > bin > reset-test-list.rs. So we need to support this use case first of all - binaries in src/bin of a workspace member.

Support examples (in workspace members)

Now, when I run cargo run --example:

$ cargo run --example
error: "--example" takes one argument.
Available examples:
    plus3

Hmm - that's really interesting! There is no such example at root level, under example > plus3.rs. What gives? It looks like this is actually an example from a workspace member, tensorflow > examples > plus3.rs. So we will also need to support such examples within workspace members as well.

Describe the solution you'd like

All runnable targets are included in output when rx is entered in a terminal.

Describe alternatives you've considered

n/a

Additional context