feat: Add banner infra.

src/Ursa/Controls/Banner.cs

@@ -0,0 +1,44 @@
+using Avalonia;
+using Avalonia.Controls;
+
+namespace Ursa.Controls;
+
+public enum BannerType
+{
+    None,
+    Info,
+    Warning,
+    Danger,
+    Success,
+}
+public class Banner: ContentControl
+{
+    public static readonly StyledProperty<bool> CanCloseProperty = AvaloniaProperty.Register<Banner, bool>(
+        nameof(CanClose));
+
+    public bool CanClose
+    {
+        get => GetValue(CanCloseProperty);
+        set => SetValue(CanCloseProperty, value);
+    }
+
+    public static readonly StyledProperty<bool> ShowIconProperty = AvaloniaProperty.Register<Banner, bool>(
+        nameof(ShowIcon));
+
+    public bool ShowIcon
+    {
+        get => GetValue(ShowIconProperty);
+        set => SetValue(ShowIconProperty, value);
+    }
+
+    public static readonly StyledProperty<object?> HeaderProperty = AvaloniaProperty.Register<Banner, object?>(
+        nameof(Header));
+
+    public object? Header
+    {
+        get => GetValue(HeaderProperty);
+        set => SetValue(HeaderProperty, value);
+    }
+    
+    
+}