Move AccentColorConverter in Avalonia.Controls.Primitives.Converters namespace

This better hides these special-purpose converters

src/Avalonia.Controls.ColorPicker/ColorPreviewer/ColorPreviewer.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Globalization;
 using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives.Converters;
 using Avalonia.Input;
 using Avalonia.Media;
 

src/Avalonia.Controls.ColorPicker/Converters/AccentColorConverter.cs

@@ -3,7 +3,7 @@ using System.Globalization;
 using Avalonia.Data.Converters;
 using Avalonia.Media;
 
-namespace Avalonia.Controls.Primitives
+namespace Avalonia.Controls.Primitives.Converters
 {
     /// <summary>
     /// Creates an accent color for a given base color value and step parameter.

src/Avalonia.Controls.ColorPicker/Themes/Default/ColorPreviewer.xaml

@@ -1,10 +1,10 @@
 <Styles xmlns="https://github.com/avaloniaui"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-        xmlns:primitives="using:Avalonia.Controls.Primitives"
+        xmlns:pc="using:Avalonia.Controls.Primitives.Converters"
         x:CompileBindings="True">
 
   <Styles.Resources>
-    <primitives:AccentColorConverter x:Key="AccentColor" />
+    <pc:AccentColorConverter x:Key="AccentColor" />
   </Styles.Resources>
 
   <Style Selector="ColorPreviewer">

src/Avalonia.Controls.ColorPicker/Themes/Fluent/ColorPreviewer.xaml

@@ -1,10 +1,10 @@
 <Styles xmlns="https://github.com/avaloniaui"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-        xmlns:primitives="using:Avalonia.Controls.Primitives"
+        xmlns:pc="using:Avalonia.Controls.Primitives.Converters"
         x:CompileBindings="True">
 
   <Styles.Resources>
-    <primitives:AccentColorConverter x:Key="AccentColor" />
+    <pc:AccentColorConverter x:Key="AccentColor" />
   </Styles.Resources>
 
   <Style Selector="ColorPreviewer">