Don't log from property accessors in the ILLink task. (dotnet#109948)

When executing a remote iOS build from Windows on macOS, the ILLink task is instantiated on the remote macOS machine using a json deserializer.

This means that the properties will be read and written to before the task has been fully initialized, and this happens:

```
Newtonsoft.Json.JsonSerializationException: Error getting value from 'ILLinkPath' on 'Xamarin.MacDev.Tasks.ILLink'.
 ---> System.InvalidOperationException: Task attempted to log before it was initialized. Message was: ILLink.Tasks path: ~/Library/Caches/Xamarin/XMA/Agents/Build/net/illink.dll
   at Microsoft.Build.Shared.ErrorUtilities.ThrowInvalidOperation(String resourceName, Object[] args)
   at Microsoft.Build.Utilities.TaskLoggingHelper.LogMessage(MessageImportance importance, String message, Object[] messageArgs)
   at ILLink.Tasks.ILLink.get_ILLinkPath()
   at Newtonsoft.Json.Serialization.ExpressionValueProvider.GetValue(Object target)
   --- End of inner exception stack trace ---
   at Newtonsoft.Json.Serialization.ExpressionValueProvider.GetValue(Object target)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.SetPropertyValue(JsonProperty property, JsonConverter propertyConverter, JsonContainerContract containerContract, JsonProperty containerProperty, JsonReader reader, Object target)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateObject(Object newObject, JsonReader reader, JsonObjectContract contract, JsonProperty member, String id)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
   at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
   at Newtonsoft.Json.JsonSerializer.Deserialize(JsonReader reader, Type objectType)
   at Xamarin.Messaging.Build.Serialization.TaskSerializer.Deserialize(String content, Type taskType) in D:\a\_work\1\s\src\MSBuild\Xamarin.Messaging.Build.Common\Serialization\TaskSerializer.cs:line 25
   at Xamarin.Messaging.Build.TaskRunner.Execute(String taskName, String inputs) in [...]xamarin-macios/msbuild/Messaging/Xamarin.Messaging.Build/TaskRunner.cs:line 42
   at Xamarin.Messaging.Build.ExecuteTaskMessageHandler.<>c__DisplayClass5_0.<ExecuteAsync>b__0() in [...]xamarin-macios/msbuild/Messaging/Xamarin.Messaging.Build/Handlers/ExecuteTaskMessageHandler.cs:line 40
   at System.Threading.Tasks.Task`1.InnerInvoke()
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of stack trace from previous location ---
   at Xamarin.Messaging.Build.ExecuteTaskMessageHandler.ExecuteAsync(ExecuteTaskMessage message) in [...]xamarin-macios/msbuild/Messaging/Xamarin.Messaging.Build/Handlers/ExecuteTaskMessageHandler.cs:line 28
   at Xamarin.Messaging.Client.RequestHandler`2.HandleAsync(TMessage message) in D:\a\_work\1\s\src\Xamarin.Messaging.Client\Handlers\RequestHandler.cs:line 68
   at Xamarin.Messaging.Client.MessageHandlerManager.<>c__DisplayClass12_1`2.<<RegisterHandlerAsync>b__2>d.MoveNext() in D:\a\_work\1\s\src\Xamarin.Messaging.Client\MessageHandlerManager.cs:line 96
--- End of stack trace from previous location ---
   at Xamarin.Messaging.Client.MessagingClient.ReplyAsync[TRequest,TResponse](IRequest`1 request, MessagePriority priority, Func`1 replyFunctionAsync) in D:\a\_work\1\s\src\Xamarin.Messaging.Client\MessagingClient.cs:line 351: 11/18/2024 10:23:11Z
```

So move the logging statement to when it the property in question is used.

src/tools/illink/src/ILLink.Tasks/LinkTask.cs

@@ -270,11 +270,7 @@ public string ILLinkPath {
 #pragma warning restore IL3000 // Avoid accessing Assembly file path when publishing as a single file
 
 				// IL Linker always runs on .NET Core, even when using desktop MSBuild to host ILLink.Tasks.
-				string path = Path.Combine (Path.GetDirectoryName (taskDirectory), "net", "illink.dll");
-
-				Log.LogMessage(MessageImportance.Normal, $"ILLink.Tasks path: {path}");
-
-				_illinkPath = path;
+				_illinkPath = Path.Combine (Path.GetDirectoryName (taskDirectory), "net", "illink.dll");
 
 				return _illinkPath;
 			}
@@ -289,7 +285,10 @@ private static string Quote (string path)
 		protected override string GenerateCommandLineCommands ()
 		{
 			var args = new StringBuilder ();
-			args.Append (Quote (ILLinkPath));
+			var path = ILLinkPath;
+			args.Append (Quote (path));
+			Log.LogMessage(MessageImportance.Normal, $"ILLink.Tasks path: {path}");
+
 			return args.ToString ();
 		}