[BUG] Styles from cellStyleXfs are not preserved

## 🐛 Bug Report

Cells with a cell style that has a xfId attribute are actually getting their styles from the cellStyleXfs section of the `styles.xml`. Right now ExcelJs does not preserve the styles from that section, so saving a file that uses them, will result in styles getting lost.

## Steps To Reproduce

Open a xlsx file that uses cellStyleXfs styles (for example cell fills) and save it with ExcelJs. The saved file will not have these cell styles.

## The expected behaviour:

The saved file should look the same as the original file.

## Possible solution (optional, but very helpful):

The original styles in cellStyleXfs should be preserved. `xfId` attributes of cellXfs should also be preserved. Ideally it should be possible to change or delete these in code.

https://github.com/exceljs/exceljs/blob/5bed18b45e824f409b08456b59b87430ded023ab/lib/xlsx/xform/style/styles-xform.js#L151

Start by reading lib/xlsx/xform/style/styles-xform.js around line 151 and inspect how styles.xml cellStyleXfs and cellXfs are handled. Reproduce the issue with an XLSX file using cellStyleXfs, such as a cell fill, then verify that saving with ExcelJS preserves the appearance and xfId attributes.

Written by the indexing model from the issue text.