Created Unassigned: Cell ranges are not supported in the PRODUCT function [9469]

Hi.

If you run this code, everything will be OK.

```
var book = new XLWorkbook();

var ws = book.AddWorksheet("ws");

ws.Cell("A1").Value = 2;
ws.Cell("B1").Value = 3;
ws.Cell("C1").FormulaA1 = "PRODUCT(A1,B1,4)";

var result = ws.Cell("C1").GetDouble();

Assert.IsTrue(result == 24);
```
But if you try to use a range (A1:B1 instead of A1,B1), then only the first cell is evaluated.
```
var book = new XLWorkbook();

var ws = book.AddWorksheet("ws");

ws.Cell("A1").Value = 2;
ws.Cell("B1").Value = 3;
ws.Cell("C1").FormulaA1 = "PRODUCT(A1:B1,4)";

var result = ws.Cell("C1").GetDouble();

Assert.IsTrue(result == 24);
```