Implement scenario test for file-based apps

Recent VMR changes have shown issues with some file based apps. It would be good to add a file-based app scenario test. The file based app directly 'executes' a .cs file. Example: `dotnet run HelloWorld.cs'. The specification is here: https://github.com/dotnet/sdk/blob/main/documentation/general/dotnet-run-file.md

Because this is a scenario test, it should also be complex enough to exercise some additional functionality. Consider an application that exercises a dotnet package search against a well-known package (e.g. `Microsoft.NETCore.App.Ref`), downloads the package at a specific, well known version, and then prints some information about the package.