Support getting a nature iterator.

PkmnLibSharp/Library/NatureLibrary.cs

@@ -62,6 +62,17 @@ namespace PkmnLibSharp.Library
             return val.PtrString()!;
         }
 
+        public IEnumerable<string> GetNatures()
+        {
+            var count = Pkmnlib.Generated.NatureLibrary.GetNatureCount(Ptr);
+            var ptr = IntPtr.Zero;
+            for (ulong i = 0; i < count; i++)
+            {
+                Pkmnlib.Generated.NatureLibrary.GetNatureByIndex(Ptr, i, ref ptr).Assert();
+                yield return ptr.PtrString()!;
+            }
+        }
+
         protected override void DeletePtr()
         {
             Pkmnlib.Generated.NatureLibrary.Destruct(Ptr);