Add evaluateFmt to xlsx options, default to true.
If evaluateFmt === false, do not evaluate the format to create the value, instead return the format in the ‘rawnf’ field.
Remove evaluateFmt option. Add skipEmptyCells opt

For now dont support evaluateFmt=false options.
Use skipRawnf=true to not generate the rawnf attribute on the cell
Use skipEmptyCells=true to not generate the cells with no value.
Support number formats with milliseconds.
remove the logging of issues when evaluating fmt, as it used to be