Switched the color of the selection rectangle to use the system accent color (#2650)

Author: yaira2

Files/Views/LayoutModes/GenericFileBrowser.xaml

@@ -194,7 +194,7 @@
                             <FontIcon FontFamily="{StaticResource FluentUIGlyphs}" Glyph="&#xea55;" />
                         </MenuFlyoutItem.Icon>
                     </MenuFlyoutItem>
-                    <MenuFlyoutSeparator x:Name="NewMenuFileFolderSeparator"/>
+                    <MenuFlyoutSeparator x:Name="NewMenuFileFolderSeparator" />
                     <MenuFlyoutItem
                         x:Name="NewFile"
                         x:Uid="BaseLayoutContextFlyoutNewFile"
@@ -922,7 +922,8 @@
                 Canvas.Top="0"
                 Width="0"
                 Height="0"
-                Fill="#AA0078d7"
+                Fill="{ThemeResource SystemAccentColor}"
+                Opacity=".5"
                 Stroke="#FF0066cc"
                 StrokeThickness="1" />
         </Canvas>

Files/Views/LayoutModes/GridViewBrowser.xaml

@@ -170,7 +170,7 @@
                         <FontIcon FontFamily="{StaticResource FluentUIGlyphs}" Glyph="&#xea55;" />
                     </MenuFlyoutItem.Icon>
                 </MenuFlyoutItem>
-                <MenuFlyoutSeparator x:Name="NewMenuFileFolderSeparator"/>
+                <MenuFlyoutSeparator x:Name="NewMenuFileFolderSeparator" />
                 <MenuFlyoutItem
                     x:Name="NewFile"
                     x:Uid="BaseLayoutContextFlyoutNewFile"
@@ -940,7 +940,8 @@
                 Canvas.Top="0"
                 Width="0"
                 Height="0"
-                Fill="#AA0078d7"
+                Fill="{ThemeResource SystemAccentColor}"
+                Opacity=".5"
                 Stroke="#FF0066cc"
                 StrokeThickness="1" />
         </Canvas>