Update icon tint color when the user toggles Dark theme

- Reload theme in slice provider when Dark theme mode changes for slices
- Reload theme in onCreate of Panel activity for its non-slice header
- Remove applyTheme from individual slices

Test: robotest
Fixes: 153700819
Change-Id: I40a7d2817c4b9100d7b2f2962a69c8a9ce6f7906

src/com/android/settings/homepage/contextualcards/slices/BluetoothDevicesSlice.java

@@ -105,9 +105,6 @@ public class BluetoothDevicesSlice implements CustomSliceable {
             return null;
         }
 
-        // Reload theme for switching dark mode on/off
-        mContext.getTheme().applyStyle(R.style.Theme_Settings_Home, true /* force */);
-
         final ListBuilder listBuilder = new ListBuilder(mContext, getUri(), ListBuilder.INFINITY)
                 .setAccentColor(COLOR_NOT_TINTED);