fix: fix error in using relativeHeadRowIndex for writing tables only

[32154678925]

Purpose of the pull request

Fixes(#794)
When you do not write directly in the sheet, but only write data in the table and set the head, the offset value set with relativeHeadRowIndex() will make an error, and the blank line with the specified offset will be empty again between the head and the data. If the head is not set, the offset value set with relativeHeadRowIndex() will not take effect

What's changed?

Change the judgment of whether to add offset in the add method in the ExcelWriteAddExecutor class from writeSheetHolder to currentWriteHolder

Before:

WriteSheetHolder writeSheetHolder = writeContext.writeSheetHolder();
int newRowIndex = writeSheetHolder.getNewRowIndexAndStartDoWrite();
if (writeSheetHolder.isNew()
        && !writeSheetHolder.getExcelWriteHeadProperty().hasHead()) {
    newRowIndex += writeContext.currentWriteHolder().relativeHeadRowIndex();
}

After:

WriteSheetHolder writeSheetHolder = writeContext.writeSheetHolder();
WriteHolder currentWriteHolder = writeContext.currentWriteHolder();
int newRowIndex = writeSheetHolder.getNewRowIndexAndStartDoWrite();
if (currentWriteHolder.isNew()) {
    if(currentWriteHolder instanceof AbstractWriteHolder){
        AbstractWriteHolder writeHolder = (AbstractWriteHolder) currentWriteHolder;
        if(!writeHolder.getExcelWriteHeadProperty().hasHead()){
            newRowIndex += currentWriteHolder.relativeHeadRowIndex();
        }
    }
}

Checklist

• I have read the Contributor Guide.
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.