added discord game sdk

src/discord-game-sdk-cpp/user_manager.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include "types.h"
+
+namespace discord {
+
+class UserManager final {
+public:
+    ~UserManager() = default;
+
+    Result GetCurrentUser(User* currentUser);
+    void GetUser(UserId userId, std::function<void(Result, User const&)> callback);
+    Result GetCurrentUserPremiumType(PremiumType* premiumType);
+    Result CurrentUserHasFlag(UserFlag flag, bool* hasFlag);
+
+    Event<> OnCurrentUserUpdate;
+
+private:
+    friend class Core;
+
+    UserManager() = default;
+    UserManager(UserManager const& rhs) = delete;
+    UserManager& operator=(UserManager const& rhs) = delete;
+    UserManager(UserManager&& rhs) = delete;
+    UserManager& operator=(UserManager&& rhs) = delete;
+
+    IDiscordUserManager* internal_;
+    static IDiscordUserEvents events_;
+};
+
+} // namespace discord