feat(api): add auth HTTP controller with tests

backend/include/csp/controllers/auth_controller.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <drogon/HttpController.h>
+
+namespace csp::controllers {
+
+class AuthController : public drogon::HttpController<AuthController> {
+ public:
+  METHOD_LIST_BEGIN
+  ADD_METHOD_TO(AuthController::registerUser, "/api/v1/auth/register", drogon::Post);
+  ADD_METHOD_TO(AuthController::login, "/api/v1/auth/login", drogon::Post);
+  METHOD_LIST_END
+
+  void registerUser(const drogon::HttpRequestPtr& req,
+                    std::function<void(const drogon::HttpResponsePtr&)>&& cb);
+
+  void login(const drogon::HttpRequestPtr& req,
+             std::function<void(const drogon::HttpResponsePtr&)>&& cb);
+};
+
+}  // namespace csp::controllers