[Dialog] Fix crashes when colorControlHighlight is a CSL

We set ?attr/colorControlHighlight as scroll indicators' background attribute. However, on older platforms this will crash the app due to Android expects a drawable or a plain color for the background attribute.

Changes the view to TextView so it will be rendered as MaterialTextView, which supports app:backgroundTint with CSLs. Also changes the base background color to #1F000000 and the tint color to ?attr/colorForeground, which are aligned with what framework's alert dialog implementation is doing.

Resolves #2455

PiperOrigin-RevId: 423917985

lib/java/com/google/android/material/dialog/res/layout/m3_alert_dialog.xml

@@ -16,6 +16,7 @@
 -->
 <androidx.appcompat.widget.AlertDialogLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:id="@+id/parentPanel"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
@@ -30,12 +31,14 @@
       android:layout_height="wrap_content"
       android:minHeight="48dp">
 
-    <View android:id="@+id/scrollIndicatorUp"
+    <ImageView android:id="@+id/scrollIndicatorUp"
         android:layout_width="match_parent"
         android:layout_height="1dp"
         android:layout_gravity="top"
-        android:background="?attr/colorControlHighlight"
-        android:visibility="gone"/>
+        android:background="#1f000000"
+        android:visibility="gone"
+        android:contentDescription="@null"
+        app:backgroundTint="?android:attr/colorForeground"/>
 
     <androidx.core.widget.NestedScrollView
         android:id="@+id/scrollView"
@@ -70,12 +73,14 @@
       </LinearLayout>
     </androidx.core.widget.NestedScrollView>
 
-    <View android:id="@+id/scrollIndicatorDown"
+    <ImageView android:id="@+id/scrollIndicatorDown"
         android:layout_width="match_parent"
         android:layout_height="1dp"
         android:layout_gravity="bottom"
-        android:background="?attr/colorControlHighlight"
-        android:visibility="gone"/>
+        android:background="#1f000000"
+        android:visibility="gone"
+        android:contentDescription="@null"
+        app:backgroundTint="?android:attr/colorForeground"/>
 
   </FrameLayout>