cli/fork: Deprecate — heartwood

This command is confusing in name and function. Rather than creating a hard fork of a repository, with a new identity, it pushes the default branch to the local user’s namespace.

Deprecate it and add some help text.

   config    Manage your local Radicle configuration
   debug     Write out information to help debug your Radicle node remotely
   follow    Manage node follow policies
   fork      Create a fork of a repository
   id        Manage repository identities
   inbox     Manage your Radicle notifications
   init      Initialize a Radicle repository

 use radicle::rad;
 use crate::terminal as term;
 use crate::{terminal as term, warning};
 pub use args::Args;
 pub fn run(args: Args, ctx: impl term::Context) -> anyhow::Result<()> {
     warning::deprecated("rad fork", "git push");
     let profile = ctx.profile()?;
     let signer = profile.signer()?;
     let storage = &profile.storage;

 use radicle::identity::RepoId;
 const ABOUT: &str = "Create a fork of a repository";
 const ABOUT: &str = "Create a fork of a repository
 This command is deprecated and will be removed.
 Instead of using `rad fork`, use `git push` to push any references to
 your own namespace of a Radicle repository. Usually
     git push rad main
 would suffice to push the default branch (here named 'main').
 ";
 #[derive(Debug, clap::Parser)]
 #[command(about = ABOUT, disable_version_flag = true)]

     Config(config::Args),
     Debug(debug::Args),
     Follow(follow::Args),
     #[command(hide = true)] // `rad fork` command is deprecated
     Fork(fork::Args),
     Id(id::Args),
     Inbox(inbox::Args),