Enable dotnet nuget why on non-SDK style projects

[zivkan]

NuGet Product(s) Involved

dotnet.exe

The Elevator Pitch

dotnet nuget why currently requires you to point to a project file, but the .NET SDK can only evaluate SDK style projects. Many non-SDK style Visual Studio projects try to import MSBuild props/targets files that don't exist in the .NET SDK and therefore trying to read project properties (to find the assets file) fails.

dotnet nuget why is particularly useful for investigating why a package with a known vulnerability is used by a project, so allowing the command to work for non-SDK style projects will help customers investigate known vulnerabilities.

dotnet nuget why should either allow a project.assets.json file to be passed as an argument instead of a project file.

We can instruct customers that they can find the assets file location using msbuild.exe path\to\project.csproj -getProperty:ProjectAssetsFile

Additional Context and Details

No response