Improve task debugging by giving more context

<!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- Please search existing issues to avoid creating duplicates. --> <!-- Describe the feature you'd like. --> Most of this text comes from an email. The context is that I got on a phone call with a customer who was experiencing issues debugging an Azure Function App. #### The issue F5 debugging of a Function App would show: ``` > Executing task: func host start < ``` And then something saying that the last exit code was 1. It wasn’t clear what the problem was, why it was failing, and we found that this would fail on `func extensions install` and `func host install`… running the func commands in the PowerShell Integrated Console or outside of VS Code in any terminal worked just fine… #### The resolution Then we realized that the customer's default shell…….. was WSL. As you know, tasks use the default shell to run in by default. Which means that the `func` commands were being run in WSL which didn’t have the Core Tools installed in it so the Task threw an exit code of 1 because the command wasn’t found. Once Aleksandar changed his default shell back to PowerShell, everything started working again. #### The problem The lack of warning on tasks as to what went wrong is very hard to debug… see above. It took an hour and a half to make this realization... And even more of the customer's time to get to the point where they asked to get on a call... #### The ask Show the shell being used to run tasks or give more than just an exit code if possible. We need more context as what's actually going on when a task is being run. I think this is a generic problem with any extension that relies on tasks and not just the Azure Functions extension.