Revert "Using NuGet.ProjectModel from the install path to avoid versi…

[ausbin]

…on conflicts (#566)"

Without this PR, some tests such as the LoadOutdatedQSharpProject test in ProjectLoaderTests were failing as follows:

 [Warning]: MSBuild warning in C:\Program Files\dotnet\sdk\6.0.301\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.EolTargetFrameworks.targets(28,5): The target framework 'netcoreapp2.0' is out of support and will not receive security updates in the future. Please refer to https://aka.ms/dotnet-core-support for more information about the support policy.
 [Warning]: MSBuild warning in C:\Program Files\dotnet\sdk\6.0.301\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.EolTargetFrameworks.targets(28,5): The target framework 'netcoreapp2.0' is out of support and will not receive security updates in the future. Please refer to https://aka.ms/dotnet-core-support for more information about the support policy.
 [Error]: MSBuild error in C:\Program Files\dotnet\sdk\6.0.301\Sdks\Microsoft.NET.Sdk\targets\Microsoft.PackageDependencyResolution.targets(267,5): The "ResolvePackageAssets" task failed unexpectedly.
 System.IO.FileLoadException: Could not load file or assembly 'NuGet.ProjectModel, Version=6.2.1.2, Culture=neutral, PublicKeyToken=31bf3856ad364e35'. Could not find or load a specific file. (0x80131621)
 File name: 'NuGet.ProjectModel, Version=6.2.1.2, Culture=neutral, PublicKeyToken=31bf3856ad364e35'
  ---> System.IO.FileLoadException: Could not load file or assembly 'NuGet.ProjectModel, Version=6.2.1.2, Culture=neutral, PublicKeyToken=31bf3856ad364e35'.
    at System.Runtime.Loader.AssemblyLoadContext.LoadFromPath(IntPtr ptrNativeAssemblyLoadContext, String ilPath, String niPath, ObjectHandleOnStack retAssembly)
    at System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyPath(String assemblyPath)
    at Microsoft.Build.Shared.MSBuildLoadContext.Load(AssemblyName assemblyName)
    at System.Runtime.Loader.AssemblyLoadContext.ResolveUsingLoad(AssemblyName assemblyName)
    at System.Runtime.Loader.AssemblyLoadContext.Resolve(IntPtr gchManagedAssemblyLoadContext, AssemblyName assemblyName)
    at Microsoft.NET.Build.Tasks.ResolvePackageAssets.CacheReader.CreateReaderFromMemory(ResolvePackageAssets task, Byte[] settingsHash)
    at Microsoft.NET.Build.Tasks.ResolvePackageAssets.CacheReader..ctor(ResolvePackageAssets task)
    at Microsoft.NET.Build.Tasks.ResolvePackageAssets.ReadItemGroups()
    at Microsoft.NET.Build.Tasks.ResolvePackageAssets.ExecuteCore()
    at Microsoft.NET.Build.Tasks.TaskBase.Execute()
    at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
    at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask)
 [Error]: Failed to resolve assembly references for project 'C:\Users\t-aadams\Documents\qsharp-compiler\src\QsCompiler\Tests.LanguageServer\bin\Debug\net6.0\TestProjects\test9\test9.csproj'.

This reverts commit 5fc3bab, aka PR #566, which looks like it was intended to resolve this issue in the past. But from printfs I added, I don't think that additional code was doing anything in this newer version of .NET to locate NuGet assemblies required by msbuild. I don't know why, but this PR will remove that code as it no longer seems necessary to me.

To buy some time for an msbuild god's help, we can upgrade our version of NuGet.ProjectModel. It has already been referenced in the language server project file since 0b3d4b3 anyway.

Testing

• Ran language server locally via VSCode
• Ran all QsCompiler unit tests and they passed.

[bettinaheim]

Hm, I am not sure this change here will always work correctly - I believe the locator throws if registering defaults is called multiple times or too late. I suggest to keep it as an AssemblyInitialize method, though I may be wrong about the need/benefits.

[cgranade]

I ran into some cases where AssemblyInitialize was not being respected correctly; on the IQ# kernel, isolated the call from unit testing harness to RegisterDefaults in a Lazy<VisualStudioInstance> property on a static class.

[ausbin]

I just pushed up a new version. Is that what you meant, @cgranade?