ContentDialog FlowDirection does not follow the XamlRoot.Content FlowDirection

[Gaoyifei1011]

Describe the bug

ContentDialog FlowDirection does not follow the XamlRoot.Content FlowDirection
ContentDialog FlowDirection 并不跟随 XamlRoot.Content 的 FlowDirection

As shown in the figure, when ContentDialog.XamlRoot is mounted to Window.Content, when ContentDialog is displayed and the FlowDirection of Window.Content is RTL, The ContentDialog is unchanged
如图所示，ContentDialog.XamlRoot 挂载到 Window.Content 时，显示 ContentDialog 时，Window.Content 的 FlowDirection 为 RTL 时，ContentDialog 没有变化

Steps to reproduce the bug

See describe

Expected behavior

ContentDialog FlowDirection should follow the XamlRoot.Content FlowDirection
ContentDialog FlowDirection 应该跟随 XamlRoot.Content 的 FlowDirection

Screenshots

NuGet package version

WinUI 3 - Windows App SDK 1.6 Preview 1: 1.6.240807006-preview1

Windows version

Windows 11 (22H2): Build 22621

Additional context

Also exists in Windows App SDK 1.5 and UWP (Including WinUI 2)