feat(event): add game_start event with exec cfg after loading end

gamestart.cfg and maps_gamestart/*.cfg

Author: anf3is

src/game/client/swarm/clientmode_asw.cpp

@@ -434,6 +434,7 @@ void ClientModeASW::Init()
 	gameeventmanager->AddListener( this, "mission_failed", false );
 	gameeventmanager->AddListener( this, "asw_mission_restart", false );
 	gameeventmanager->AddListener( this, "game_newmap", false );
+	gameeventmanager->AddListener( this, "game_start", false );
 	HOOK_MESSAGE( ASWBlur );
 	HOOK_MESSAGE( ASWCampaignCompleted );
 	HOOK_MESSAGE( ASWTechFailure );
@@ -826,6 +827,11 @@ void ClientModeASW::FireGameEvent( IGameEvent *event )
 		// BenLubar: Support configloader config files from that one HUD mod: https://steamcommunity.com/app/630/discussions/0/522728268792383118/
 		engine->ClientCmd_Unrestricted( VarArgs( "execifexists configloader/maps/%s\n", engine->GetLevelNameShort() ) );
 	}
+	else if ( Q_strcmp( "game_start", eventname ) == 0 )
+	{
+		engine->ClientCmd("execifexists gamestart\n");
+		engine->ClientCmd_Unrestricted( VarArgs( "execifexists maps_gamestart/%s\n", engine->GetLevelNameShort() ) );
+	}
 
 	if ( !Q_strcmp( "achievement_earned", eventname ) )
 	{

src/game/shared/swarm/asw_gamerules.cpp

@@ -3121,6 +3121,12 @@ void CAlienSwarm::UpdateLaunching()
 		{
 			RunScriptFunctionInListenerScopes( "OnGameplayStart", NULL, 0, NULL );
 		}
+
+		IGameEvent *event = gameeventmanager->CreateEvent( "game_start" );
+		if ( event )
+		{
+			gameeventmanager->FireEvent( event );
+		}
 	}
 	else
 	{