Error output discards actual error message (feature request)

Hi,

I had a problem with the extension not finding any tests. As it turned out in actuality my windows env-variables were broken. But I would have never been able to debug that, because the extension discards the native error thrown during test discovery and instead prints a generic, not very helpful error message.

Could you please change this to include the actual error thrown into the message? This cost me a few hours to debug, because I searched in the completely wrong direction - with the error message it would have taken me half an hour...

In my case, all I did was change the error output in the testDiscovery.js file at line 46 to this:
```js
logger_1.Logger.LogError(`Error while executing ${command}: ${err}`, stdout);
```
This gave me the information needed to debug my error.

Regards,
Daniel