feat(opnsense-config): add caddy module with configuration management

Introduce a new Caddy module within opnsense-config to manage Caddy server configurations. This includes enabling/disabling Caddy, setting ports, and reloading/restarting the service via OPNsense shell commands. Additionally, provide a sample Caddy configuration file for PXE booting and a test file in the pxe-http-files directory.

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

@@ -3,7 +3,7 @@ use std::{sync::Arc, time::Duration};
 use crate::{
     config::{SshConfigManager, SshCredentials, SshOPNSenseShell},
     error::Error,
-    modules::{dhcp::DhcpConfig, dns::DnsConfig, load_balancer::LoadBalancerConfig, tftp::TftpConfig},
+    modules::{caddy::CaddyConfig, dhcp::DhcpConfig, dns::DnsConfig, load_balancer::LoadBalancerConfig, tftp::TftpConfig},
 };
 use log::{info, trace};
 use opnsense_config_xml::OPNsense;
@@ -42,6 +42,10 @@ impl Config {
         TftpConfig::new(&mut self.opnsense, self.shell.clone())
     }
 
+    pub fn caddy(&mut self) -> CaddyConfig {
+        CaddyConfig::new(&mut self.opnsense, self.shell.clone())
+    }
+
     pub fn load_balancer(&mut self) -> LoadBalancerConfig {
         LoadBalancerConfig::new(&mut self.opnsense, self.shell.clone())
     }
@@ -50,6 +54,17 @@ impl Config {
         self.shell.upload_folder(source, destination).await
     }
 
+    // Here maybe we should take ownership of `mut self` instead of `&mut self`
+    // I don't think there can be faulty pointers to previous versions of the config but I have a
+    // hard time wrapping my head around it right now :
+    // - the caller has a mutable reference to us
+    // - caller gets a reference to a piece of configuration (.haproxy.general.servers[0])
+    // - caller calls install_package wich reloads the config from remote
+    // - haproxy.general.servers[0] does not exist anymore
+    // - broken?
+    //
+    // Although I did not try explicitely the above workflow so maybe rust prevents taking a
+    // read-only reference across the &mut call
     pub async fn install_package(&mut self, package_name: &str) -> Result<(), Error> {
         info!("Installing opnsense package {package_name}");
         let output = self.shell