cli/init: Remove unnecessary `clap` conflict rule — heartwood

This removes an unnecessary conflict rule from the mutually exclusive arguments --private and --public. Conflict rules only need to be set for one of the two arguments, they do not need to be set for each.

     #[arg(long, conflicts_with = "public")]
     private: bool,
     /// Set repository visibility to *public*
     #[arg(long, conflicts_with = "private")]
     #[arg(long)]
     public: bool,
     /// Setup repository as an existing Radicle repository
     ///