Improve color contrast of reset button in SUI (#17912)

Adds a theme resource for the color of the reset button in the settings UI.

Closes #17902

(cherry picked from commit 0bd19e9)
Service-Card-Id: PVTI_lADOAF3p4s4AmhmszgTTb0s
Service-Version: 1.21

Author: carlos-zamora

src/cascadia/TerminalSettingsEditor/SettingContainerStyle.xaml

@@ -44,6 +44,9 @@
             <StaticResource x:Key="SettingContainerMessageForeground"
                             ResourceKey="TextFillColorPrimaryBrush" />
 
+            <StaticResource x:Key="SettingContainerResetButtonIconForeground"
+                            ResourceKey="SystemAccentColorDark2" />
+
         </ResourceDictionary>
         <ResourceDictionary x:Key="HighContrast">
             <Style x:Key="SecondaryTextBlockStyle"
@@ -73,6 +76,9 @@
                             ResourceKey="SystemColorWindowTextColorBrush" />
             <StaticResource x:Key="SettingContainerMessageForeground"
                             ResourceKey="SystemColorWindowTextColorBrush" />
+
+            <StaticResource x:Key="SettingContainerResetButtonIconForeground"
+                            ResourceKey="SystemAccentColorLight1" />
         </ResourceDictionary>
         <ResourceDictionary x:Key="Dark">
             <Style x:Key="SecondaryTextBlockStyle"
@@ -106,6 +112,9 @@
                             ResourceKey="TextFillColorPrimaryBrush" />
             <StaticResource x:Key="SettingContainerMessageForeground"
                             ResourceKey="TextFillColorPrimaryBrush" />
+
+            <StaticResource x:Key="SettingContainerResetButtonIconForeground"
+                            ResourceKey="SystemAccentColorLight2" />
         </ResourceDictionary>
     </ResourceDictionary.ThemeDictionaries>
 
@@ -136,7 +145,7 @@
 
     <Style x:Key="SettingContainerFontIconStyle"
            TargetType="FontIcon">
-        <Setter Property="Foreground" Value="{StaticResource SystemAccentColor}" />
+        <Setter Property="Foreground" Value="{ThemeResource SettingContainerResetButtonIconForeground}" />
         <Setter Property="FontSize" Value="11" />
         <Setter Property="FontFamily" Value="{ThemeResource SymbolThemeFontFamily}" />
     </Style>