Support creating a napi crate as a workspace member

[YassinEldeeb]

Currently, incorporating a napi.rs crate as a workspace member is tricky, especially configuring the generated github CI to point to the correct paths, it'd be great if the CLI asked "Is workspace? (assuming running from the root) y/N" and then it goes and modifies everything needed from paths in the CI to adding it as a member of the workspace.