Make RBTree node fields internal again

Prevents someone from accidentaly messing with them and leaving the tree in a invalid state

Ryujinx.Common/Collections/IntrusiveRedBlackTreeNode.cs

@@ -5,10 +5,10 @@ namespace Ryujinx.Common.Collections
     /// </summary>
     public class IntrusiveRedBlackTreeNode<T> where T : IntrusiveRedBlackTreeNode<T>
     {
-        public bool Color = true;
-        public T Left;
-        public T Right;
-        public T Parent;
+        internal bool Color = true;
+        internal T Left;
+        internal T Right;
+        internal T Parent;
 
         public T Predecessor => IntrusiveRedBlackTreeImpl<T>.PredecessorOf((T)this);
         public T Successor => IntrusiveRedBlackTreeImpl<T>.SuccessorOf((T)this);