[BUG] Style not implemented for cell

## 🐛 Bug Report

in the file cell-xform.js I fix the next part.
Add validation for variable (**cellStylesCache?**)

```
if (cellStylesCache?.has(modelStyleKey)) {
model.styleId = cellStylesCache.get(modelStyleKey);
}

if (!model.styleId) {
const styleId = options.styles.addStyleModel(modelStyle, getEffectiveCellType(model));
if (styleId) {
model.styleId = styleId;
cellStylesCache?.set(modelStyleKey, styleId);
}
}
```

it's work for me now