cargo-chef isn't local registry aware

[prestontw]

Link to minimal repo: https://github.com/prestontw/cargo-chef-vendored-repo

I've vendored the dependencies of a small Rocket app using cargo vendor. I've then updated .cargo/config.toml so that cargo build uses the local dependencies. Trying to run cargo chef errors with checksum changes (since cargo chef has replaced all of the lib.rs files in the dependencies with empty files?).

I'm thinking if we make cargo chef aware of .cargo/config.toml, we will know not to skelefy these vendored files.

Aside: using cargo-local-registry is fine since it stores dependencies in zipped files, so cargo chef doesn't skelefy them.

[LukeMathWalker]

.cargo/config.toml is already part of the recipe file, so it should be possible to make this work without any changes to the CLI parameters.