[android] Use default background color on bottomsheet

Signed-off-by: Jean-Baptiste <jeanbaptiste.charron@outlook.fr>

android/app/src/main/res/layout-land/layout_nav.xml

@@ -41,5 +41,5 @@
     android:layout_width="0dp"
     android:layout_height="0dp"
     android:layout_gravity="bottom|start"
-    android:background="?colorSurfaceContainerLow"/>
+    android:background="?appBackground"/>
 </FrameLayout>

android/app/src/main/res/layout/layout_nav.xml

@@ -40,5 +40,5 @@
     android:layout_width="0dp"
     android:layout_height="0dp"
     android:layout_gravity="bottom|center"
-    android:background="?colorSurfaceContainerLow"/>
+    android:background="?appBackground"/>
 </FrameLayout>

android/app/src/main/res/values-night/themes.xml

@@ -151,7 +151,7 @@
     <item name="colorSurfaceContainerHigh">@color/md_theme_surfaceContainerHigh</item>
     <item name="colorSurfaceContainerHighest">@color/md_theme_surfaceContainerHighest</item>
 
-    <item name="appBackground">?android:attr/colorBackground</item>
+    <item name="appBackground">@color/bg_app</item>
   </style>
 
   <style name="MwmTheme" parent="MwmTheme.Base"/>

android/app/src/main/res/values/styles.xml

@@ -287,13 +287,13 @@
   </style>
 
   <style name="MwmWidget.BottomSheetDialog" parent="Widget.Material3.BottomSheet.Modal">
-    <item name="backgroundTint">?colorSurfaceContainerLow</item>
+    <item name="backgroundTint">?appBackground</item>
     <item name="elevationOverlayEnabled">false</item>
     <item name="shapeAppearance">@style/ShapeAppearance.Material3.LargeComponent</item>
   </style>
 
   <style name="MwmWidget.BottomSheet" parent="MwmWidget.BottomSheetDialog">
-    <item name="android:background">?colorSurfaceContainerLow</item>
+    <item name="android:background">?appBackground</item>
     <item name="behavior_hideable">false</item>
   </style>