Remove NamedColors<T> usages

src/ImageSharp.Drawing/Processing/GradientBrushBase.cs

@@ -49,6 +49,8 @@ namespace SixLabors.ImageSharp.Processing
         internal abstract class GradientBrushApplicatorBase<TPixel> : BrushApplicator<TPixel>
             where TPixel : struct, IPixel<TPixel>
         {
+            private static readonly TPixel Transparent = Color.Transparent.ToPixel<TPixel>();
+
             private readonly ColorStop[] colorStops;
 
             private readonly GradientRepetitionMode repetitionMode;
@@ -103,7 +105,7 @@ namespace SixLabors.ImageSharp.Processing
                         case GradientRepetitionMode.DontFill:
                             if (positionOnCompleteGradient > 1 || positionOnCompleteGradient < 0)
                             {
-                                return NamedColors<TPixel>.Transparent;
+                                return Transparent;
                             }
 
                             break;

tests/ImageSharp.Tests/TestUtilities/Attributes/WithSolidFilledImagesAttribute.cs

@@ -99,7 +99,7 @@ namespace SixLabors.ImageSharp.Tests
         /// </summary>
         /// <param name="width">The width of the requested image</param>
         /// <param name="height">The height of the requested image</param>
-        /// <param name="colorName">The referenced color name (name of property in <see cref="NamedColors{TPixel}")/></param>
+        /// <param name="colorName">The referenced color name (name of property in <see cref="Color"/>).</param>
         /// <param name="pixelTypes">The requested pixel types</param>
         /// <param name="additionalParameters">Additional theory parameter values</param>
         public WithSolidFilledImagesAttribute(
@@ -119,7 +119,7 @@ namespace SixLabors.ImageSharp.Tests
         /// <param name="memberData">The member data to apply to theories</param>
         /// <param name="width">The width of the requested image</param>
         /// <param name="height">The height of the requested image</param>
-        /// <param name="colorName">The referenced color name (name of property in <see cref="NamedColors{TPixel}")/></param>
+        /// <param name="colorName">The referenced color name (name of property in <see cref="Color"/>).</param>
         /// <param name="pixelTypes">The requested pixel types</param>
         /// <param name="additionalParameters">Additional theory parameter values</param>
         public WithSolidFilledImagesAttribute(