Review lifecycle of services registered in the DI container (#459)

Author: joegoldman2

Src/Fido2.AspNet/Fido2NetLibBuilderExtensions.cs

@@ -23,7 +23,7 @@ public static IFido2NetLibBuilder AddFido2(this IServiceCollection services, ICo
 
     private static void AddServices(this IServiceCollection services)
     {
-        services.AddTransient<IFido2, Fido2>();
+        services.AddScoped<IFido2, Fido2>();
         services.AddSingleton<IMetadataService, NullMetadataService>(); //Default implementation if we choose not to enable MDS
         services.TryAddSingleton<ISystemClock, SystemClock>();
     }
@@ -42,14 +42,14 @@ public static IFido2NetLibBuilder AddFido2(this IServiceCollection services, Act
 
     public static void AddCachedMetadataService(this IFido2NetLibBuilder builder, Action<IFido2MetadataServiceBuilder> configAction)
     {
-        builder.AddMetadataService<DistributedCacheMetadataService>();
+        builder.Services.AddScoped<IMetadataService, DistributedCacheMetadataService>();
 
         configAction(new Fido2NetLibBuilder(builder.Services));
     }
 
     public static IFido2MetadataServiceBuilder AddFileSystemMetadataRepository(this IFido2MetadataServiceBuilder builder, string directoryPath)
     {
-        builder.Services.AddTransient<IMetadataRepository, FileSystemMetadataRepository>(r =>
+        builder.Services.AddScoped<IMetadataRepository, FileSystemMetadataRepository>(provider =>
         {
             return new FileSystemMetadataRepository(directoryPath);
         });
@@ -62,7 +62,7 @@ public static IFido2MetadataServiceBuilder AddConformanceMetadataRepository(
         HttpClient client = null,
         string origin = "")
     {
-        builder.Services.AddTransient<IMetadataRepository>(provider =>
+        builder.Services.AddScoped<IMetadataRepository>(provider =>
         {
             return new ConformanceMetadataRepository(client, origin);
         });
@@ -80,15 +80,10 @@ public static IFido2MetadataServiceBuilder AddFidoMetadataRepository(this IFido2
         if (clientBuilder != null)
             clientBuilder(httpClientBuilder);
 
-        builder.Services.AddTransient<IMetadataRepository, Fido2MetadataServiceRepository>();
+        builder.Services.AddScoped<IMetadataRepository, Fido2MetadataServiceRepository>();
 
         return builder;
     }
-
-    private static void AddMetadataService<TService>(this IFido2NetLibBuilder builder) where TService : class, IMetadataService
-    {
-        builder.Services.AddScoped<IMetadataService, TService>();
-    }
 }
 
 public interface IFido2NetLibBuilder