friend: Implement stubs for all service functions

- Add implementations for all previously unimplemented IFriendService functions
- Create IDaemonSuspendSessionService class and implement CreateDaemonSuspendSessionService
- Restructure code to separate method declarations from implementations
- Add helper structs/payloads for various friend-related data structures
- Update function documentation and logging messages

Signed-off-by: Zephyron <zephyron@citron-emu.org>

src/core/hle/service/friend/friend.h

@@ -1,4 +1,5 @@
 // SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 citron Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #pragma once
@@ -21,6 +22,7 @@ public:
 
         void CreateFriendService(HLERequestContext& ctx);
         void CreateNotificationService(HLERequestContext& ctx);
+        void CreateDaemonSuspendSessionService(HLERequestContext& ctx);
 
     protected:
         std::shared_ptr<Module> module;

src/core/hle/service/friend/friend_interface.cpp

@@ -1,4 +1,5 @@
 // SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
+// SPDX-FileCopyrightText: Copyright 2025 citron Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include "core/hle/service/friend/friend_interface.h"
@@ -10,7 +11,7 @@ Friend::Friend(std::shared_ptr<Module> module_, Core::System& system_, const cha
     static const FunctionInfo functions[] = {
         {0, &Friend::CreateFriendService, "CreateFriendService"},
         {1, &Friend::CreateNotificationService, "CreateNotificationService"},
-        {2, nullptr, "CreateDaemonSuspendSessionService"},
+        {2, &Friend::CreateDaemonSuspendSessionService, "CreateDaemonSuspendSessionService"},
     };
     RegisterHandlers(functions);
 }