chore: Move opnsense credential secret from example into domain. There is an architectural problem around secrets still but its definitely something we want to manage for the user

examples/okd_pxe/src/topology.rs

@@ -1,28 +1,22 @@
 use cidr::Ipv4Cidr;
 use harmony::{
-    hardware::{FirewallGroup, HostCategory, Location, PhysicalHost, SwitchGroup},
+    config::secret::OPNSenseFirewallCredentials,
+    hardware::{Location, SwitchGroup},
     infra::opnsense::OPNSenseManagementInterface,
     inventory::Inventory,
     topology::{HAClusterTopology, LogicalHost, UnmanagedRouter},
 };
 use harmony_macros::{ip, ipv4};
-use harmony_secret::{Secret, SecretManager};
-use serde::{Deserialize, Serialize};
+use harmony_secret::SecretManager;
 use std::{net::IpAddr, sync::Arc};
 
-#[derive(Secret, Serialize, Deserialize, Debug, PartialEq)]
-struct OPNSenseFirewallConfig {
-    username: String,
-    password: String,
-}
-
 pub async fn get_topology() -> HAClusterTopology {
     let firewall = harmony::topology::LogicalHost {
         ip: ip!("192.168.1.1"),
         name: String::from("opnsense-1"),
     };
 
-    let config = SecretManager::get::<OPNSenseFirewallConfig>().await;
+    let config = SecretManager::get::<OPNSenseFirewallCredentials>().await;
     let config = config.unwrap();
 
     let opnsense = Arc::new(