Fix MUX CommandBar style not being applied to TextControl flyouts. (#…

…4586)

* Add TextControlCommandBar* flyout to Mux

* save state

* Fix TextCommandBarFlyout included in mux theme resources to be a Mux type instead of a Wux type.

dev/CommonStyles/Common_themeresources.xaml

@@ -1,7 +1,8 @@
 <!-- Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT License. See LICENSE in the project root for license information. -->
 <ResourceDictionary
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
-    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:contract7Present="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractPresent(Windows.Foundation.UniversalApiContract,7)" xmlns:controls="using:Microsoft.UI.Xaml.Controls">
     <!--
         SystemControlTransparentBrush isn't defined in TH2. In RS1 and RS2, it's set to Transparent
         for all the themes. We explicitly set it here to ensure it's always defined.
@@ -49,6 +50,10 @@
 
     <x:Boolean x:Key="ThemeShadowIsUsingDropShadows">True</x:Boolean>
 
+
+    <controls:TextCommandBarFlyout x:Key="TextControlCommandBarContextFlyout" Placement="BottomEdgeAlignedLeft" />
+    <controls:TextCommandBarFlyout x:Key="TextControlCommandBarSelectionFlyout" Placement="TopEdgeAlignedLeft" />
+
     <Style TargetType="LoopingSelector">
         <Setter Property="ShouldLoop" Value="True" />
         <Setter Property="UseSystemFocusVisuals" Value="{StaticResource UseSystemFocusVisuals}" />