feat: .NET SDK 9+ compatibility

src/bsp-server/Handlers/BuildInitializeHandler.cs

@@ -1,4 +1,5 @@
-using BaseProtocol;
+using System.Text.Json;
+using BaseProtocol;
 using bsp4csharp.Protocol;
 using Microsoft.Build.Locator;
 
@@ -16,9 +17,34 @@ public Task<InitializeBuildResult> HandleRequestAsync(InitializeBuildParams requ
     {
         _initializeManager.SetInitializeParams(request);
 
+        if (MSBuildLocator.IsRegistered)
+        {
+            throw new ServerNotInitializedException("MSBuild instance already registered.");
+        }
+
         // this has to be loaded before we try to use any Microsoft.Build.* references
-        var msBuildInstance = MSBuildLocator.RegisterDefaults();
-        context.Logger.LogInformation("MSBuild instance used: {}", msBuildInstance.MSBuildPath);
+        var instanceQueryOptions = new VisualStudioInstanceQueryOptions
+        {
+            DiscoveryTypes = DiscoveryType.DotNetSdk,
+            WorkingDirectory = request.RootUri.AbsolutePath,
+        };
+
+        var msBuildInstances = MSBuildLocator.QueryVisualStudioInstances(instanceQueryOptions)
+            .OrderByDescending(x => x.Version);
+        var msBuildInstance = msBuildInstances
+            .FirstOrDefault();
+        foreach (var instance in msBuildInstances)
+        {
+            context.Logger.LogInformation("MSBuild instance found: {}", JsonSerializer.Serialize(instance));
+        }
+
+        if (msBuildInstance == null)
+        {
+            throw new ServerNotInitializedException("MSBuild instance could not be found on your system.");
+        }
+
+        MSBuildLocator.RegisterInstance(msBuildInstance);
+        context.Logger.LogInformation("MSBuild instance used: {}", JsonSerializer.Serialize(msBuildInstance));
 
         var serverCapabilities = _initializeManager.GetInitializeResult();
 

src/bsp-server/Logging/MSBuildLogger.cs

@@ -14,12 +14,17 @@
     private readonly ICollection<string> _diagnosticKeysCollection = [];
     private int Warnings = 0;
     private int Errors = 0;
-    private readonly DateTime _buildStartTimestamp;
-    private readonly string[] _targetsOfInterest = ["Clean", "Build", "Restore"];
+    private TimeProvider _timeProvider = TimeProvider.System;
+    private DateTimeOffset _buildStartTimestamp;
+    private readonly string[] _targetsOfInterest = [
+        "Clean",
+        "Build",
+        "Restore",
+    ];
 
     public LoggerVerbosity Verbosity { get; set; } = LoggerVerbosity.Normal;
 
     public string Parameters { get; set; } = string.Empty;
 
     public void Initialize(IEventSource eventSource)
     {
@@ -36,8 +41,12 @@
 
     private void TargetStarted(object sender, TargetStartedEventArgs e)
     {
-        if (_targetsOfInterest.Contains(e.TargetName, StringComparer.InvariantCultureIgnoreCase) &&
-            e.BuildReason == TargetBuiltReason.None)
+        if (_buildStartTimestamp == null)
+        {
+            _buildStartTimestamp = _timeProvider.GetUtcNow();
+        }
+
+        if (_targetsOfInterest.Contains(e.TargetName, StringComparer.InvariantCultureIgnoreCase))
         {
             var taskId = new TaskId { Id = e.ProjectFile + "#" + e.TargetName + "#" + e.ThreadId };
             var taskStartParams = new TaskStartParams