[Pre-RFC] `cargo package` should include fewer files by default

Vorpal:

I would prefer if it instead of removing these files became possible or even easy to execute the tests of all your dependencies.

If there is a desire to run something like cargo test --include-deps, then that also runs into dependency resolution. As of today, Cargo only resolves dev-dependencies for your own packages. This means they aren't in your Cargo.lock or vendored by cargo vendor and cargo will error if somehow you get it to try to use one of those dependencies.