Add interfaces for C++ worker cluster mode (#8859)

cpp/include/ray/api/ray_config.h

@@ -1,5 +1,7 @@
 
 #pragma once
+#include <memory>
+#include <string>
 
 namespace ray {
 namespace api {
@@ -11,9 +13,16 @@ enum class WorkerMode { NONE, DRIVER, WORKER };
 /// TODO(Guyang Song): Make configuration complete and use to initialize.
 class RayConfig {
  public:
-  WorkerMode workerMode = WorkerMode::DRIVER;
+  WorkerMode worker_mode = WorkerMode::DRIVER;
 
-  RunMode runMode = RunMode::SINGLE_PROCESS;
+  RunMode run_mode = RunMode::SINGLE_PROCESS;
+
+  std::string redis_address;
+
+  static std::shared_ptr<RayConfig> GetInstance();
+
+ private:
+  static std::shared_ptr<RayConfig> config_;
 };
 
 }  // namespace api