Assembly output path not being provided to extensions with new MSBuild project types

Reported on [VS Feedback](https://developercommunity.visualstudio.com/content/problem/49891/assembly-reference-not-being-provided-to-extension.html):

Attempting to use an extension that needs to analyze a compiled assembly will fail for projects that build into a subdirectory of debug or release. EG:
Could not find file: 'C:\Users\David\Documents\Visual Studio 2017\Projects\NetTally\NetTally.Core\bin\Debug\netstandard1.3\' Could not find file: 'C:\Users\David\Documents\Visual Studio 2017\Projects\NetTally\NetTally.Console\bin\Debug\netcoreapp1.1\'
This occurs with the Portability Analysis extension, and the ILSpy extension. It appears to pass only the final directory, with the target project type (eg: netstandard1.3 or netcoreapp1.1), and not the actual assembly or DLL.
It functions properly for standard .NET Framework projects which do not create that extra subdirectory, for both extensions tested. As such, it appears that the proper value is not being passed on request, but instead only the incomplete path value.