Added Notification Popup for Achievement Unlocked

Added an OnScreenDisplay message to HandleAchievementTriggeredEvent to display a message when a player has unlocked an achievement. The message includes the title of the achievement and its point value based on the game data. To match RetroAchievements' website interface, the message is blue if the unlock is casual and gold for challenge.

Source/Core/Core/AchievementManager.cpp

@@ -5,6 +5,8 @@
 
 #include "Core/AchievementManager.h"
 
+#include <fmt/format.h>
+
 #include <rcheevos/include/rc_hash.h>
 
 #include "Common/HttpRequest.h"
@@ -14,6 +16,7 @@
 #include "Core/PowerPC/MMU.h"
 #include "Core/System.h"
 #include "DiscIO/Volume.h"
+#include "VideoCommon/OnScreenDisplay.h"
 #include "VideoCommon/VideoEvents.h"
 
 static constexpr bool hardcore_mode_enabled = false;
@@ -506,6 +509,11 @@ void AchievementManager::HandleAchievementTriggeredEvent(const rc_runtime_event_
     return;
   it->second.session_unlock_count++;
   m_queue.EmplaceItem([this, runtime_event] { AwardAchievement(runtime_event->id); });
+  AchievementId game_data_index = it->second.game_data_index;
+  OSD::AddMessage(fmt::format("Unlocked: {} ({})", m_game_data.achievements[game_data_index].title,
+                              m_game_data.achievements[game_data_index].points),
+                  OSD::Duration::VERY_LONG,
+                  (hardcore_mode_enabled) ? OSD::Color::YELLOW : OSD::Color::CYAN);
   ActivateDeactivateAchievement(runtime_event->id, Config::Get(Config::RA_ACHIEVEMENTS_ENABLED),
                                 Config::Get(Config::RA_UNOFFICIAL_ENABLED),
                                 Config::Get(Config::RA_ENCORE_ENABLED));