Fix loading tileRectsIds in auto-layer rule definition (#7)

When creating rules for auto-layers of an IntGrid in LDtk and saving it,
then Korge-ldtk was not able to load that ldtk file any more due to
differences between json file and the implemented json schema.

The name of the property is different in json file from LDtk, thus
@SerialName was updated. Also the type of the tileIDS field needs to
be an array of array of Ints.

korge-ldtk/src/commonMain/kotlin/korlibs/korge/ldtk/LDTKJson.kt

@@ -1072,8 +1072,8 @@ data class AutoLayerRuleDefinition (
     /**
      * Array of all the tile IDs. They are used randomly or as stamps, based on `tileMode` value.
      */
-    @SerialName("tileIds")
-    val tileIDS: IntArray,
+    @SerialName("tileRectsIds")
+    val tileIDS: List<IntArray>,
 
     /**
      * Defines how tileIds array is used Possible values: `Single`, `Stamp`