Support for new `slnx` solution format

[HakamFostok]

NuGet Product(s) Involved

NuGet.exe

The Elevator Pitch

Intorduction

"Solution File Persistence Model" is a new feature and still a Preview Feature in Visual Studio.
It enables a new format for the solution file based on XML format.
Here is more information
https://www.youtube.com/watch?v=wzMMclD8QsI
https://www.youtube.com/watch?v=D0MxmDWk4t0

---

I enabled this preview feature and it is working well.
I tried the following statement from the command line

dotnet list MySolution.slnx package --vulnerable --include-transitive

and I get the following error

error: Parameter "xml" cannot be null.

here is a screenshot

I understand that this is still a preview feature, but I would like to see NuGet support it (not in near future, but hopefully sometime)

Thank you all for the great efforts

[nkolev92]

@baronfel provided us with some links:

library source: https://github.com/microsoft/vs-solutionpersistence
usage of the library to read projects: https://github.com/dotnet/sdk/blob/25fd857f19cab0a7c38cce55e9cc8806cd65cc54/src/Cli/dotnet/commands/dotnet-sln/list/Program.cs#L42-L57

We'd probably need to make this change at https://github.com/NuGet/NuGet.Client/blob/bfa944e99acda45819787beb6a3ffa82cabea69d/src/NuGet.Core/NuGet.CommandLine.XPlat/Utility/MSBuildAPIUtility.cs#L82-L85 at minimum.

We should ensure that all dotnet nuget commands support slnx.
Related: #11789

[baronfel]

The tracking issue in vs-solutionpersistence for slnf support is microsoft/vs-solutionpersistence#85.