feat: Add main application views and structure

- Implemented CreateInstanceView for creating new instances.
- Added HostsView for managing SSH hosts with CRUD operations.
- Created InstancesView for displaying and managing instances.
- Developed LogsView for viewing operation logs.
- Introduced SecretsView for managing secrets associated with hosts.
- Established SettingsView for configuring application settings.
- Created MainWindow as the main application window with navigation.
- Added app manifest and configuration files for logging and settings.

OTSSignsOrchestrator.Desktop/Views/SettingsView.axaml.cs

@@ -0,0 +1,11 @@
+using Avalonia.Controls;
+
+namespace OTSSignsOrchestrator.Desktop.Views;
+
+public partial class SettingsView : UserControl
+{
+    public SettingsView()
+    {
+        InitializeComponent();
+    }
+}