`pijul channel new` to create new, empty channels

Dependencies

• [2] PGERZ3KJ Channel renaming (also do not create a new channel when recording on a channel that doesn't exist)
• [*] SXEYMYF7 Fixing the bad changes in history (unfortunately, by rebooting).
• [*] VQPAUKBQ channel switch as an alias to reset

Change contents

• edit in pijul/src/commands/channel.rs at line 32
  [5.999]

  [4.187365]
  + /// Create a new, empty channel.

  + #[clap(name = "switch")]

  + New { name: String },
• edit in pijul/src/commands/channel.rs at line 98
  [2.446]

  [4.189246]
  + }

  + Some(SubCommand::New { name }) => {

  + let repo = Repository::find_root(self.repo_path).await?;

  + let mut txn = repo.pristine.mut_txn_begin()?;

  + if txn.load_channel(&name)?.is_some() {

  + bail!("Channel {} already exists", name)

  + }

  + txn.open_or_create_channel(&name)?;

  + txn.commit()?;