Updated the control gallery demo list with new/updated tag

Author: naveenkumar-sanjeevirayan

maui/samples/Gallery/Converters/StringToVisibilityConverter .cs

@@ -0,0 +1,18 @@
+using System.Globalization;
+
+namespace Syncfusion.Maui.ControlsGallery.Converters
+{
+	public class StringToVisibilityConverter : IValueConverter
+	{
+		public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+		{
+			return !string.IsNullOrEmpty(value as string);
+		}
+
+		public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+		{
+			return null;
+		}
+
+	}
+}