Implement registries ...

[przygienda]

Now that multiple registries seems stable it would be good to allow that. Just take registry description with -Zunstable and use that URL ...

[g-k]

👍 I don't have time to work on this right now, but I'd accept a PR.

Assuming these docs are up to date we could:

• [ ] add an optional --registry arg
• [ ] read the registry url from .cargo/config
• [ ] read the auth token (if any) from the .cargo/credentials

Reading the toml .cargo files should resolve cargo's hierarchical-structure. We might be able to use the https://docs.rs/cargo_metadata/ crate.

Use https://github.com/alexcrichton/cargo-local-registry for local testing.

We could also add a --registry-url option to replace the hardcoded default at https://github.com/g-k/cargo-show/blob/master/src/main.rs#L17

[przygienda]

sigh, no cycles here either unless it becomes pressing. Agree with plan ...