[WIP] Improve error message "Failed to find all versions of .NET Core MSBuild. Call to hostfxr_resolve_sdk2. There may be more details in stderr"

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original issue description:

When opening a project with:

using var workspace = MSBuildWorkspace.Create();
return await workspace.OpenProjectAsync(projectFilePath, cancellationToken: cancellationToken);

if the app is trying to open a project targeting a SDK > at the app running, the following exception is thrown:

Microsoft.CodeAnalysis.MSBuild.RemoteInvocationException: An exception of type System.InvalidOperationException was
thrown: Failed to find all versions of .NET Core MSBuild. Call to hostfxr_resolve_sdk2. There may be more details in
stderr.
   at Microsoft.CodeAnalysis.MSBuild.RpcClient.InvokeCoreAsync(Int32 targetObject, String methodName, List`1 parameters,
Type expectedReturnType, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.RpcClient.InvokeAsync[T](Int32 targetObject, String methodName, List`1 parameters,
CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.RemoteBuildHost.LoadProjectFileAsync(String projectFilePath, String languageName,
CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.DoOperationAndReportProgressAsync[
TResult](ProjectLoadOperation operation, String projectPath, String targetFramework, Func`1 doFunc)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.LoadProjectFileInfosAsync(String projectPath,
DiagnosticReportingOptions reportingOptions, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.LoadProjectInfosFromPathAsync(String projectPath,
DiagnosticReportingOptions reportingOptions, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.Worker.LoadAsync(CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.LoadProjectInfoAsync(String projectFilePath, ProjectMap
projectMap, IProgress`1 progress, ILogger msbuildLogger, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildProjectLoader.LoadProjectInfoAsync(String projectFilePath, ProjectMap
projectMap, IProgress`1 progress, ILogger msbuildLogger, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace.OpenProjectAsync(String projectFilePath, ILogger msbuildLogger,
IProgress`1 progress, CancellationToken cancellationToken)

It would be nice to improve the message with something along the lines of Ensure the target framework version of your app is equal or superior to the SDK version of the project to load

Fixes #331.

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