Smaller initial size for ModifiedRangeList & directly inherit range list (#2663)

This fixes a potential regression with the new range list changes, where the cost for creating new ones would be rather large due to creating a 1024 size array. Also reduces cost for range list inheritance by using the first existing range list as a base, rather than creating a new one then adding both lists to it.

The growth size for the RangeList is now identical to its initial size. Every 32 elements was probably a little too common - now it is 1024 for most things and 8 for the buffer modified range list.

The Unmapped and SyncMethod methods have been changed to ensure that they behave properly if the range list is set null. Cleaned up a few calls to use the null-conditional operator.

Ryujinx.Memory/Range/RangeList.cs

@@ -33,18 +33,22 @@ namespace Ryujinx.Memory.Range
             }
         }
 
+        private const int BackingInitialSize = 1024;
         private const int ArrayGrowthSize = 32;
-        private const int BackingGrowthSize = 1024;
 
         private RangeItem<T>[] _items;
+        private readonly int _backingGrowthSize;
+
         public int Count { get; protected set; }
 
         /// <summary>
         /// Creates a new range list.
         /// </summary>
-        public RangeList()
+        /// <param name="backingInitialSize">The initial size of the backing array</param>
+        public RangeList(int backingInitialSize = BackingInitialSize)
         {
-            _items = new RangeItem<T>[BackingGrowthSize];
+            _backingGrowthSize = backingInitialSize;
+            _items = new RangeItem<T>[backingInitialSize];
         }
 
         /// <summary>
@@ -68,7 +72,7 @@ namespace Ryujinx.Memory.Range
         {
             if (Count + 1 > _items.Length)
             {
-                Array.Resize(ref _items, _items.Length + ArrayGrowthSize);
+                Array.Resize(ref _items, _items.Length + _backingGrowthSize);
             }
 
             if (index >= Count)