string.Join() with alternative joins for last

```csharp
var array = new string[]{"abc", "def", "ghi"};
var listString = string.Join(", ", array);
// Produces:
// abc, def, ghi
```

But, what if want the last join to be `", and "` instead of just `", "` like the rest? So that the output is:
```
abc, def, and ghi
```