Fix ClassCastException

See #6577 (comment)

java.lang.ClassCastException: android.widget.ImageButton cannot be cast to androidx.appcompat.widget.AppCompatImageButton
	at org.schabi.newpipe.player.Player.onRepeatModeChanged(Player.java:2263)
	at com.google.android.exoplayer2.ExoPlayerImpl.lambda$setRepeatMode$2(ExoPlayerImpl.java:564)
	at com.google.android.exoplayer2.-$$Lambda$ExoPlayerImpl$rgrcbaqP9Y8LgzdByBnAfUO4ydU.invokeListener(lambda)
	at com.google.android.exoplayer2.BasePlayer$ListenerHolder.invoke(BasePlayer.java:279)
	at com.google.android.exoplayer2.ExoPlayerImpl.invokeAll(ExoPlayerImpl.java:1498)
	at com.google.android.exoplayer2.ExoPlayerImpl.lambda$notifyListeners$6(ExoPlayerImpl.java:1318)
	at com.google.android.exoplayer2.-$$Lambda$ExoPlayerImpl$b59raXxaB-trjwE5bgpZInm1QnU.run(lambda)
	at com.google.android.exoplayer2.ExoPlayerImpl.notifyListeners(ExoPlayerImpl.java:1328)
	at com.google.android.exoplayer2.ExoPlayerImpl.notifyListeners(ExoPlayerImpl.java:1318)
	at com.google.android.exoplayer2.ExoPlayerImpl.setRepeatMode(ExoPlayerImpl.java:564)
	at com.google.android.exoplayer2.SimpleExoPlayer.setRepeatMode(SimpleExoPlayer.java:1636)
	at org.schabi.newpipe.player.Player.setRepeatMode(Player.java:2253)
	at org.schabi.newpipe.player.Player.onRepeatClicked(Player.java:2232)
	at org.schabi.newpipe.player.Player.onBroadcastReceived(Player.java:1123)
	at org.schabi.newpipe.player.Player.access$200(Player.java:190)
	at org.schabi.newpipe.player.Player$3.onReceive(Player.java:1060)
	at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:1185)
	... 7 more

app/src/main/res/layout-large-land/player.xml

@@ -531,7 +531,7 @@
                 app:tint="@color/white"
                 app:srcCompat="@drawable/ic_close" />
 
-            <ImageButton
+            <androidx.appcompat.widget.AppCompatImageButton
                 android:id="@+id/repeatButton"
                 android:layout_width="50dp"
                 android:layout_height="50dp"