Inserting single-cell prompt into cell that already has a single-cell prompt does not retrigger calculation.

Works fine for `=PROMPT.TOROW()`, `=PROMPT.TOCOLUMN()`, and `=PROMPT.TORANGE()`:

 src\Cellm\AddIn\UserInterface\Ribbon\RibbonPromptGroup.cs:251
```csharp
if (currentOutputShape == targetOutputShape)
{
    // Just recalculate
    ExcelDnaUtil.Application.ActiveCell.Calculate();
    return;
}
```