make sure the multiblock uuid gets saved to disk when it changes

Author: thiakil

src/main/java/mekanism/common/tile/prefab/TileEntityMultiblock.java

@@ -125,7 +125,11 @@ protected boolean onUpdateServer() {
                 needsPacket = true;
             }
             if (multiblock.inventoryID != null) {
+                UUID oldCachedID = cachedID;
                 cachedID = multiblock.inventoryID;
+                if (oldCachedID != cachedID) {
+                    markForSave();
+                }
                 if (isMaster()) {
                     if (multiblock.tick(level)) {
                         needsPacket = true;