Make "Player notification" PreferenceScreen searchable

Author: Stypox

app/src/main/res/values/settings_keys.xml

@@ -1325,4 +1325,5 @@
         <item>@string/wifi_only</item>
     </string-array>
     <string name="streams_notifications_channels_key">streams_notifications_channels</string>
+    <string name="player_notification_screen_key">player_notification_screen</string>
 </resources>

app/src/main/res/xml/appearance_settings.xml

@@ -24,6 +24,7 @@
         app:iconSpaceReserved="false" />
 
     <PreferenceScreen
+        android:key="@string/player_notification_screen_key"
         android:fragment="org.schabi.newpipe.settings.PlayerNotificationSettingsFragment"
         android:summary="@string/settings_category_player_notification_summary"
         android:title="@string/settings_category_player_notification_title"