Only show "Enqueue next" when in the middle of the queue

Add a check that the queue position is not the last in the queue before
showing "Enqueue next".

Previously the "Enqueue next" action would always be shown if the queue
length was greater than one, this meant even if you were at the end of
the queue (when "Enqueue" would have the same effect as "Enqueue next")
the action would still be shown.

app/src/main/java/org/schabi/newpipe/info_list/dialog/InfoItemDialog.java

@@ -252,10 +252,11 @@ public final class InfoItemDialog {
          * @return the current {@link Builder} instance
          */
         public Builder addEnqueueEntriesIfNeeded() {
-            if (PlayerHolder.getInstance().isPlayQueueReady()) {
+            final PlayerHolder holder = PlayerHolder.getInstance();
+            if (holder.isPlayQueueReady()) {
                 addEntry(StreamDialogDefaultEntry.ENQUEUE);
 
-                if (PlayerHolder.getInstance().getQueueSize() > 1) {
+                if (holder.getQueuePosition() < holder.getQueueSize() - 1) {
                     addEntry(StreamDialogDefaultEntry.ENQUEUE_NEXT);
                 }
             }

app/src/main/java/org/schabi/newpipe/player/helper/PlayerHolder.java

@@ -92,6 +92,13 @@ public final class PlayerHolder {
         return player.getPlayQueue().size();
     }
 
+    public int getQueuePosition() {
+        if (player == null || player.getPlayQueue() == null) {
+            return 0;
+        }
+        return player.getPlayQueue().getIndex();
+    }
+
     public void setListener(@Nullable final PlayerServiceExtendedEventListener newListener) {
         listener = newListener;