Save id_token in Apple provider

If SaveTokens is set to true, save the id_token in the Apple provider like the SuperOffice provider does.

Addresses #556.

Author: martincostello

src/AspNet.Security.OAuth.Apple/AppleAuthenticationHandler.cs

@@ -339,6 +339,13 @@ private async Task<HandleRequestResult> HandleRemoteAuthenticateAsync(
                     }
                 }
 
+                string? idToken = tokens.Response.RootElement.GetString("id_token");
+
+                if (!string.IsNullOrEmpty(idToken))
+                {
+                    authTokens.Add(new AuthenticationToken() { Name = "id_token", Value = idToken });
+                }
+
                 properties.StoreTokens(authTokens);
             }
 

test/AspNet.Security.OAuth.Providers.Tests/Apple/AppleTests.cs

@@ -45,6 +45,7 @@ protected internal override void RegisterAuthentication(AuthenticationBuilder bu
             {
                 ConfigureDefaults(builder, options);
                 options.ClientId = "com.martincostello.signinwithapple.test.client";
+                options.SaveTokens = true;
             });
         }
 

test/AspNet.Security.OAuth.Providers.Tests/SuperOffice/SuperOfficeTests.cs

@@ -35,6 +35,7 @@ protected internal override void RegisterAuthentication(AuthenticationBuilder bu
                 ConfigureDefaults(builder, options);
 
                 options.ClientId = "gg454918d75b1b53101065c16ee51123";
+                options.SaveTokens = true;
                 options.TokenValidationParameters.ValidAudience = options.ClientId;
                 options.TokenValidationParameters.ValidIssuer = "https://sod.superoffice.com";
             });