chore: Add msbuild diagnostic logging (#74)

This PR adds logging msbuild workspace diagnostics after the index
operation finishes. This is important to figure out why a index command
may not have found all the proper files. MSBuild logs diagnostics in two
levels Failure and Warning.

When MSBuild reports a Failure I am logging these as an Error since
these will block indexing of that project. For example

```
fail: Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace[0] Failure: Msbuild failed when processing the file '/Users/mmanela/dev/me/diffplex/DiffPlex.App/DiffPlex.App.csproj' with message: /usr/local/share/dotnet/sdk/8.0.307/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.Sdk.FrameworkReferenceResolution.targets: (90, 5): To build a project targeting Windows on this operating system, set the EnableWindowsTargeting property to true. (occurred 1 times)
```



However, when MSBuild reports a warning, I am logging at the debug level
since these are noisier and don't often relate to issues that are
blocking indexing. For example

```
dbug: Microsoft.CodeAnalysis.MSBuild.MSBuildWorkspace[0] Warning: Found project reference without a matching metadata reference: /Users/mmanela/dev/me/diffplex/DiffPlex/DiffPlex.csproj (occurred 9 times)
```

Author: mmanela

ScipDotnet/IndexCommandHandler.cs

@@ -1,6 +1,7 @@
 using System.Diagnostics;
 using Google.Protobuf;
 using Microsoft.CodeAnalysis.Elfie.Extensions;
+using Microsoft.CodeAnalysis.MSBuild;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.FileSystemGlobbing;
 using Microsoft.Extensions.Hosting;
@@ -49,6 +50,33 @@ public static async Task<int> Process(
             nugetConfigPath
         );
         await ScipIndex(host, options);
+
+
+        // Log msbuild workspace diagnostic information after the index command finishes
+        // We log the MSBuild failures as error since they are often blocking issues
+        // preventing indexing. However, we log msbuild warnings as debug since they
+        // do not block indexing usually and are much noisier
+        var workspaceLogger = host.Services.GetRequiredService<ILogger<MSBuildWorkspace>>();
+        var workspaceService = host.Services.GetRequiredService<MSBuildWorkspace>();
+        if (workspaceService.Diagnostics.Any())
+        {
+            var diagnosticGroups = workspaceService.Diagnostics
+                .GroupBy(d => new { d.Kind, d.Message })
+                .Select(g => new { g.Key.Kind, g.Key.Message, Count = g.Count() });
+            foreach (var diagnostic in diagnosticGroups)
+            {
+                var message = $"{diagnostic.Kind}: {diagnostic.Message} (occurred {diagnostic.Count} times)";
+                if (diagnostic.Kind == Microsoft.CodeAnalysis.WorkspaceDiagnosticKind.Failure)
+                {
+                    workspaceLogger.LogError(message);
+                }
+                else
+                {
+                    workspaceLogger.LogDebug(message);
+                }
+            }
+        }
+
         return 0;
     }