Tabbed bottom sheet adjustments (#6309)

* SimpleNavigationView: Don't set background and elevation

* Add divider for tabs in bottom sheet

app/src/main/res/drawable/transparent_tabs_background.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <shape
+            android:shape="rectangle">
+            <solid android:color="@android:color/transparent"/>
+        </shape>
+    </item>
+    <item
+        android:gravity="bottom">
+        <shape>
+            <size android:height="1dp" />
+            <solid android:color="?attr/colorSurfaceVariant" />
+        </shape>
+    </item>
+</layer-list>