Add EnsureCapacity method

Recyclable.Collections/RecyclableList.cs

@@ -209,6 +209,22 @@ namespace Recyclable.Collections
                         }
                 }
 
+                /// <summary>
+                /// Ensures that the capacity of this list is at least the specified value.
+                /// </summary>
+                /// <param name="capacity">The minimum capacity to ensure.</param>
+                /// <returns>The new capacity of the list.</returns>
+                [MethodImpl(MethodImplOptions.AggressiveInlining)]
+                public int EnsureCapacity(int capacity)
+                {
+                        if (capacity > _capacity)
+                        {
+                                _capacity = RecyclableListHelpers<T>.EnsureCapacity(this, _count, checked((int)BitOperations.RoundUpToPowerOf2((uint)capacity)));
+                        }
+
+                        return _capacity;
+                }
+
                 public bool IsReadOnly => false;
 
 		[MethodImpl(MethodImplOptions.AggressiveInlining)]