fluent2 - fix check glyph type and size

src/Avalonia.Themes.Fluent2/Controls/CheckBox.xaml

@@ -12,11 +12,14 @@
     </Border>
   </Design.PreviewWith>
 
+  <StreamGeometry x:Key="CheckBoxIndeterminatePathData">M3.997 13H20a1 1 0 1 0 0-2H3.997a1 1 0 1 0 0 2Z</StreamGeometry>
   <StreamGeometry x:Key="CheckMarkPathData">M5.5 10.586 1.707 6.793A1 1 0 0 0 .293 8.207l4.5 4.5a1 1 0 0 0 1.414 0l11-11A1 1 0 0 0 15.793.293L5.5 10.586Z</StreamGeometry>
   <x:Double x:Key="CheckBoxMinHeight">32</x:Double>
   <!-- WinUI forces MinWidth=120, which breaks desktop form layouts (and v1 never had it).
        Deliberately 0 here; override this resource to restore the WinUI metric. -->
   <x:Double x:Key="CheckBoxMinWidth">0</x:Double>
+  <x:Double x:Key="CheckBoxSize">20</x:Double>
+  <x:Double x:Key="CheckBoxGlyphSize">12</x:Double>
 
   <!-- WinUI reference: CheckBox_themeresources.xaml (DefaultCheckBoxStyle), tag winui3/release/1.5.2 -->
   <ControlTheme x:Key="{x:Type CheckBox}" TargetType="CheckBox">
@@ -50,12 +53,12 @@
                     BorderThickness="{DynamicResource CheckBoxBorderThemeThickness}"
                     CornerRadius="{TemplateBinding CornerRadius}"
                     UseLayoutRounding="False"
-                    Height="20"
-                    Width="20" />
+                    Height="{DynamicResource CheckBoxSize}"
+                    Width="{DynamicResource CheckBoxSize}" />
 
             <Viewbox UseLayoutRounding="False">
               <Panel>
-                <Panel Height="16" Width="16" />
+                <Panel Height="{DynamicResource CheckBoxGlyphSize}" Width="{DynamicResource CheckBoxGlyphSize}" />
                 <Path x:Name="CheckGlyph"
                       Opacity="0"
                       Fill="{DynamicResource CheckBoxCheckGlyphForegroundUnchecked}"
@@ -239,7 +242,7 @@
 
       <Style Selector="^ /template/ Path#CheckGlyph">
         <Setter Property="Fill" Value="{DynamicResource CheckBoxCheckGlyphForegroundIndeterminate}" />
-        <Setter Property="Data" Value="M1536 1536v-1024h-1024v1024h1024z" />
+        <Setter Property="Data" Value="{DynamicResource CheckBoxIndeterminatePathData}" />
         <Setter Property="Width" Value="7" />
         <Setter Property="Opacity" Value="1" />
       </Style>