Update the Auth CMake with federated changes, and fix tests

Update the CMakeLists for Auth to include the source file for the federated auth provider. Changed the creation of the fake OAuth provider data in the tests to not use an initializer list, as that was causing issues when building for open source, and seems to require a newer version of C++.

PiperOrigin-RevId: 260794967

Author: a-maurice

auth/CMakeLists.txt

@@ -101,6 +101,7 @@ set(desktop_SRCS
     src/desktop/auth_desktop.cc
     src/desktop/auth_providers/email_auth_provider.cc
     src/desktop/auth_providers/facebook_auth_provider.cc
+    src/desktop/auth_providers/federated_auth_provider.cc
     src/desktop/auth_providers/gamecenter_auth_provider.cc
     src/desktop/auth_providers/github_auth_provider.cc
     src/desktop/auth_providers/google_auth_provider.cc