feat(harmony): add OPNSense shell command execution score

Introduces a new `OPNSenseShellCommandScore` to execute shell commands on an OPNSense device within the Harmony framework. This allows for custom command execution as part of the scoring and interpretation process, enhancing the flexibility and functionality of the system.

harmony-rs/opnsense-config/src/config/config.rs

@@ -181,6 +181,10 @@ impl Config {
 
         Ok(OPNsense::from(xml))
     }
+
+    pub async fn run_command(&self, command: &str) -> Result<String, Error> {
+        self.shell.exec(command).await
+    }
 }
 
 #[cfg(test)]