Fix #2521 reported by @nirkal \n\n ✨ (ServiceCollectionExtensions.cs, TfsGitRepositoryTool.cs): add TfsChangeSetMappingTool to service collection and ensure required service retrieval

Add `TfsChangeSetMappingTool` to the service collection to enable its configuration and usage within the application. Change the retrieval method of `TfsChangeSetMappingTool` from `GetService` to `GetRequiredService` to ensure that the service is available and to prevent potential null reference exceptions. This change enhances the robustness and configurability of the application by ensuring necessary services are properly registered and retrieved.

Author: MrHinsh

src/MigrationTools.Clients.TfsObjectModel/ServiceCollectionExtensions.cs

@@ -30,6 +30,7 @@ public static void AddMigrationToolServicesForClientTfs_Tools(this IServiceColle
             context.AddSingleton<TfsNodeStructureTool>().AddMigrationToolsOptions<TfsNodeStructureToolOptions, TfsNodeStructureToolOptionsValidator>(configuration);
             context.AddSingleton<TfsRevisionManagerTool>().AddMigrationToolsOptions<TfsRevisionManagerToolOptions>(configuration);
             context.AddSingleton<TfsTeamSettingsTool>().AddMigrationToolsOptions<TfsTeamSettingsToolOptions>(configuration);
+            context.AddSingleton< TfsChangeSetMappingTool>().AddMigrationToolsOptions<TfsChangeSetMappingToolOptions>(configuration);
         }
 
         public static void AddMigrationToolServicesForClientTfs_Processors(this IServiceCollection context)
@@ -93,4 +94,4 @@ public static void AddMigrationToolServicesForClientLegacyAzureDevOpsObjectModel
             context.AddTransient<IWorkItemQuery, TfsWorkItemQuery>();
         }
     }
-}
+}

src/MigrationTools.Clients.TfsObjectModel/Tools/TfsGitRepositoryTool.cs

@@ -84,7 +84,7 @@ public  int Enrich(TfsProcessor processor, WorkItemData sourceWorkItem, WorkItem
             }
 
             Log.LogInformation("GitRepositoryEnricher: Enriching {Id} To fix Git Repo Links", targetWorkItem.Id);
-            var changeSetMappings = Services.GetService<TfsChangeSetMappingTool>();
+            var changeSetMappings = Services.GetRequiredService<TfsChangeSetMappingTool>();
             List<ExternalLink> newEL = new List<ExternalLink>();
             List<ExternalLink> removeEL = new List<ExternalLink>();
             int count = 0;