feat-visualization (#33)

尽管里面有点粪，但还是生成了漂亮的树，就当给树施肥了
剩下一个小问题：未考虑节点的宽度（因为名称不一样长），但目前未发现对图生成的明显影响

Co-authored-by: jackfiled <xcrenchangjun@outlook.com>
Reviewed-on: PostGuard/Canon#33
Co-authored-by: Ichirinko <1621543655@qq.com>
Co-committed-by: Ichirinko <1621543655@qq.com>

Canon.Server/Extensions/ServiceCollectionExtensions.cs

@@ -0,0 +1,20 @@
+using Canon.Server.Services;
+using MongoDB.Driver;
+
+namespace Canon.Server.Extensions;
+
+public static class ServiceProviderExtensions
+{
+    public static void AddGridFs(this IServiceCollection serviceCollection,
+        string connectionString, string databaseName)
+    {
+        serviceCollection.AddSingleton<IMongoClient, MongoClient>(
+            _ => new MongoClient(connectionString));
+
+        serviceCollection.AddScoped<GridFsService>(provider =>
+        {
+            IMongoClient client = provider.GetRequiredService<IMongoClient>();
+            return new GridFsService(client, databaseName);
+        });
+    }
+}