feat: cibtool trigger --message option — radicle-ci-broker

This makes it easier to create a trigger message to give to a CI adapter.

 use radicle_ci_broker::{
     ergo,
     msg::RequestBuilder,
     refs::{branch_ref, ref_string},
 };

     #[clap(long)]
     id_file: Option<PathBuf>,
     /// Output a trigger message for a CI adapter, instead of an event
     /// that `cib` will turn into a trigger message. Output is always to
     /// stdout. There will be one message per line in the output.
     #[clap(long)]
     message: bool,
     /// Output the event to trigger a CI run to the standard output,
     /// instead of adding to the event queue in the database.
     #[clap(long, conflicts_with = "all")]

         let event = CiEvent::branch_updated(nid, repo.id, &branch_name, oid, base)
             .map_err(TriggerError::CiEvent)?;
         if self.message {
             self.trigger_message(event, r)
         } else {
             self.trigger_event(event, args)
         }
     }
     fn trigger_message(&self, event: CiEvent, r: &ergo::Radicle) -> Result<(), TriggerError> {
         let msg = RequestBuilder::default()
             .profile(r.profile())
             .ci_event(&event)
             .build_trigger_from_ci_event()
             .map_err(TriggerError::TriggerMessage)?;
         let json = serde_json::to_string(&msg).map_err(TriggerError::MessageToJson)?;
         println!("{json}");
         Ok(())
     }
     fn trigger_event(&self, event: CiEvent, args: &Args) -> Result<(), TriggerError> {
         if self.stdout {
             let json = event.to_pretty_json().map_err(TriggerError::EventToJson2)?;
             println!("{json}");

     #[error("failed to construct a CI event")]
     CiEvent(#[source] CiEventError),
     #[error("failed to convert trigger message to JSON")]
     MessageToJson(#[source] serde_json::Error),
     #[error(transparent)]
     EventToJson2(#[from] CiEventError),

     #[error("failed to get database")]
     OpenDb(#[source] Box<CibToolError>),
     #[error("failed to create a trigger message")]
     TriggerMessage(#[source] radicle_ci_broker::msg::MessageError),
 }