Add remove border effect implementation for uwp (#1048)

Co-authored-by: Alexander Witkowski <[email protected]>

Author: Alex-Witkowski

src/CommunityToolkit/Xamarin.CommunityToolkit/Effects/RemoveBorder/RemoveBorderEffect.shared.cs

@@ -16,6 +16,9 @@ public RemoveBorderEffect()
 #elif __ANDROID__
 			if (DateTime.Now.Ticks < 0)
 				_ = new Xamarin.CommunityToolkit.Android.Effects.RemoveBorderEffect();
+#elif UWP
+			if (System.DateTime.Now.Ticks < 0)
+				_ = new Xamarin.CommunityToolkit.UWP.Effects.RemoveBorderEffect();
 #endif
 			#endregion
 		}

src/CommunityToolkit/Xamarin.CommunityToolkit/Effects/RemoveBorder/RemoveBorderEffect.uwp.cs

@@ -0,0 +1,32 @@
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Xamarin.CommunityToolkit.Effects;
+using Xamarin.Forms.Platform.UWP;
+using Effects = Xamarin.CommunityToolkit.UWP.Effects;
+
+[assembly: Xamarin.Forms.ExportEffect(typeof(Effects.RemoveBorderEffect), nameof(RemoveBorderEffect))]
+
+namespace Xamarin.CommunityToolkit.UWP.Effects
+{
+	public class RemoveBorderEffect : PlatformEffect
+	{
+		Thickness oldBorderThickness;
+
+		protected override void OnAttached()
+		{
+			if (Control is Control uwpControl)
+			{
+				oldBorderThickness = uwpControl.BorderThickness;
+				uwpControl.BorderThickness = new Thickness(0.0);
+			}
+		}
+
+		protected override void OnDetached()
+		{
+			if (Control is Control uwpControl)
+			{
+				uwpControl.BorderThickness = oldBorderThickness;
+			}
+		}
+	}
+}