feat: Improve Ubuntu installation and SSH execution

- Update example configuration comments
- Refactor server rescue check to use file_exists
- Add Ubuntu installation timeout and polling constants
- Implement non-interactive installation script execution
- Enhance SSH execution with argument parsing
- Add check to skip reinstallation if Ubuntu is already installed
- Copy SSH key to new system during installation
- Poll for installation completion with progress updates
- Use `node.exec` instead of `node.exec_interactive`
- Use `execvp` correctly for shell execution
- Recreate node connection after server reboot
- Adjust SSH wait timeout to milliseconds

examples/virt/hetzner/hetzner_example.hero

@@ -1,35 +1,34 @@
 #!/usr/bin/env hero
 
+// # Configure HetznerManager, replace with your own credentials, server id's and ssh key name and all other parameters
 
-// !!hetznermanager.configure
-// 	name:"main"
-// 	user:"krist"
-// 	whitelist:"2111181, 2392178, 2545053, 2542166, 2550508, 2550378,2550253"
-// 	password:"wontsethere"
-// 	sshkey:"kristof"
+!!hetznermanager.configure
+	user:"user_name"
+	whitelist:"server_id"
+	password:"password"
+	sshkey:"ssh_key_name"
 
-
-// !!hetznermanager.server_rescue
-//     server_name: 'kristof21'  // The name of the server to manage (or use `id`)
-//     wait: true                     // Wait for the operation to complete
-//     hero_install: true             // Automatically install Herolib in the rescue system
+!!hetznermanager.server_rescue
+    server_name: 'server_name'  // The name of the server to manage (or use `id`)
+    wait: true                     // Wait for the operation to complete
+    hero_install: true             // Automatically install Herolib in the rescue system
 
 
 // # Reset a server
-// !!hetznermanager.server_reset
-//     instance: 'main'
-//     server_name: 'your-server-name'
-//     wait: true
+!!hetznermanager.server_reset
+    instance: 'main'
+    server_name: 'server_name'
+    wait: true
 
 // # Add a new SSH key to your Hetzner account
-// !!hetznermanager.key_create
-//     instance: 'main'
-//     key_name: 'my-laptop-key'
-//     data: 'ssh-rsa AAAA...'
+!!hetznermanager.key_create
+    instance: 'main'
+    key_name: 'ssh_key_name'
+    data: 'ssh-rsa AAAA...'
 
 
 // Install Ubuntu 24.04 on a server
 !!hetznermanager.ubuntu_install
-    server_name: 'kristof2'
+    server_name: 'server_name'
     wait: true
     hero_install: true            // Install Herolib on the new OS

examples/virt/hetzner/hetzner_kristof2.vsh

@@ -60,9 +60,8 @@ mut n := b.node_new(ipaddr: serverinfo.server_ip)!
 // this will put hero in debug mode on the system
 // n.hero_install(compile: true)!
 
-n.shell('')!
-
 cl.ubuntu_install(name: name, wait: true, hero_install: true)!
+n.shell('')!
 // cl.ubuntu_install(name: 'kristof20', wait: true, hero_install: true)!
 // cl.ubuntu_install(id:2550378, name: 'kristof21', wait: true, hero_install: true)!
 // cl.ubuntu_install(id:2550508, name: 'kristof22', wait: true, hero_install: true)!