Add an option to set custom column width in Excel files

[kristjanmar]

It would be great to have an option to set custom column widths in Excel for large numbers.

Currently, large numbers in Excel get formatted as ####### if the number is too big for the column. The user then needs to expand the column width manually in order to see the number.

[jmaister]

Looks like there is some info in this github issue: SheetJS/sheetjs#1158