feat(cron): Add clear-error command handler

Part of #349. Enables `hermes cron clear-error JOB_ID` command.

hermes_cli/cron.py

@@ -303,10 +303,12 @@ def cron_command(args):
     if subcmd == "run":
         now = getattr(args, 'now', False)
         return _job_action("run", args.job_id, "Triggered", now=now)
+    if subcmd == "clear-error":
+        return _job_action("clear_error", args.job_id, "Cleared")
 
     if subcmd in {"remove", "rm", "delete"}:
         return _job_action("remove", args.job_id, "Removed")
 
     print(f"Unknown cron command: {subcmd}")
-    print("Usage: hermes cron [list|create|edit|pause|resume|run|remove|status|tick]")
+    print("Usage: hermes cron [list|create|edit|pause|resume|run|remove|clear-error|status|tick]")
     sys.exit(1)