feat(workspace): reduce manifests and dependencies for target members

[preiter93]

For the prepare command, if a --bin member is specified:

• Keep only the workspace manifests relevant to the target member
• Filter the lock file to include only dependencies used by those manifests

See https://github.com/LukeMathWalker/cargo-chef/issues/323

[preiter93]

To test it, one can install it from branch:

cargo install --git https://github.com/preiter93/cargo-chef --branch reduce-workspace