Expose cache in IngredientCollectionDiffManager

Required for CyclopsMC/IntegratedDynamics#1359

src/main/java/org/cyclops/cyclopscore/ingredient/collection/diff/IngredientCollectionDiffManager.java

@@ -43,4 +43,10 @@ public IngredientCollectionDiff<T, M> onChange(Iterator<T> newInstances) {
         return diff;
     }
 
+    public IngredientCollectionPrototypeMap<T, M> getInstancesCache() {
+        if (this.instancesCache == null) {
+            this.instancesCache = new IngredientCollectionPrototypeMap<>(this.ingredientComponent, true);
+        }
+        return this.instancesCache;
+    }
 }