Use encoding custom atom labels to check molecule edition

Current we check if the molecule was edited by using idCode. However this does not include the custom labels. This means that if they are changed we consider no changes ...


Before edition / after edition the canonized idCode with custom label should be compared

https://cheminfo.github.io/openchemlib-js/classes/Canonizer.html

Code should be something like:

```js
const canonizer = new Canonizer(molecule, {encodeAtomCustomLabels: true});
const idCode = canonizer.getIDCode();
```