refactor: use engine in main

Also introduce exit codes: 0 for success, 1 for problem in the
repository under test, 2 for engine problem.

Signed-off-by: Lars Wirzenius <liw@liw.fi>

src/msg.rs

@@ -3,8 +3,7 @@ use std::path::PathBuf;
 use radicle_ci_broker::msg::{MessageError, Request, Response, RunId, RunResult};
 
 use crate::{
-    config::ConfigError, logfile::LogError, report, runcmd::RunCmdError, runinfo::RunInfoError,
-    runspec::RunSpecError,
+    config::ConfigError, logfile::LogError, report, runinfo::RunInfoError, runspec::RunSpecError,
 };
 
 /// Read a request from stdin.
@@ -81,9 +80,6 @@ pub enum NativeMessageError {
     #[error(transparent)]
     Report(#[from] report::ReportError),
 
-    #[error(transparent)]
-    RunCmd(#[from] RunCmdError),
-
     #[error(transparent)]
     RunInfo(#[from] RunInfoError),