Add --workspace option to cargo new and cargo init

[windy1]

This pull request minimally adds a --workspace option to both cargo new and cargo init.

Related Issue: #8365

• Tests passing
• Code formatted

For example:

$ cargo new --workspace foo

Will produce:

foo
└── Cargo.toml

0 directories, 1 file

With a Cargo.toml with the contents:

[workspace]
members = []

Notes:

• The --edition option is silently ignored (perhaps this warrants a warning?)
• The --vsc option is observed because build artifacts can be created in the root workspace directory

Opinion: Wanted to start off small here, but being able to manage workspaces through cargo is a big value-add from my perspective. Not only would it provide QoL enhancements for developers using Cargo CLI, but also provide editors/IDEs a convenient way to manage them as well.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @ehuss (or someone else) soon.

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[ehuss]

Thanks for the PR! Unfortunately, I don't think we'll be able to merge this at this time. The future and design of cargo new is uncertain, and I think this has some overlap with possible directions it may go. In particular, this would probably have some interaction with templates, and may even be possible to completely implement this with templates. There's also some complications with how cargo new doesn't really work correctly inside a workspace (#6378). For now, we'd like to postpone this until there is a better understanding of how cargo new will work.

[windy1]

Thank you for the clarification @ehuss. Definitely understandable. I would just like to see workspaces better supported in cargo in general.

[ehuss]

Closing as postponed. Thanks for giving it a try, though! Hopefully we'll have bandwidth to pursue this more in the future.