Mirror Freeform's BACK icon for RTL languages

When the system language is set to Right-to-Left languages
(e.g., Arabic), the back arrow appears in the wrong direction.

To resolve this issue, set "android:autoMirrored" to true
in the vector file.

Bug: 360764398
Test: manual UI check

Change-Id: I4296c331e3957e8196c3bb6f575ed4e53fa6af99
diff --git a/libs/WindowManager/Shell/res/drawable/decor_back_button_dark.xml b/libs/WindowManager/Shell/res/drawable/decor_back_button_dark.xml
index 5ecba38..a36b21f 100644
--- a/libs/WindowManager/Shell/res/drawable/decor_back_button_dark.xml
+++ b/libs/WindowManager/Shell/res/drawable/decor_back_button_dark.xml
@@ -15,6 +15,7 @@
   -->
 
 <vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:autoMirrored="true"
         android:width="32.0dp"
         android:height="32.0dp"
         android:viewportWidth="32.0"