Static Graph restore won't warn for invalid projects

[nkolev92]

Have a sln with 2 projects, one restoreable, the other without the NuGet.targets.

Regular restore will warn https://github.com/NuGet/NuGet.Client/blob/b6ba5908951c172ed7df75e3074a7af409f743d7/src/NuGet.Core/NuGet.Build.Tasks/NuGet.targets#L282-L292, while static graph restore quietly skips the project.

cc @jeffkl

We need to understand what we want the experience to be.

[jeffkl]

This would be easy to add so yeah we just need to brainstorm on the experience