Guard against cheat codes in RetroAchievements' hardcore mode

originally I thought just blocking the cheat window would be enough, but autoloaded cheat codes could sneak through. An actual check for cheat codes being active prevents this being an issue.

src/BizHawk.Client.EmuHawk/RetroAchievements/IMainFormForRetroAchievements.cs

@@ -15,6 +15,8 @@ namespace BizHawk.Client.EmuHawk
 
 		GameInfo Game { get; }
 
+		public CheatCollection CheatList { get; }
+
 		IMovieSession MovieSession { get; }
 
 		FirmwareManager FirmwareManager { get; }

src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.Hardcore.cs

@@ -77,6 +77,12 @@ namespace BizHawk.Client.EmuHawk
 				return;
 			}
 
+			if (CheatList.AnyActive)
+			{
+				HandleHardcoreModeDisable("Using cheat codes while in hardcore mode is not allowed.");
+				return;
+			}
+
 			// suppress rewind and frame advance hotkeys
 			_hardcoreHotkeyOverrides.FrameTick();
 			_hardcoreHotkeyOverrides.SetButton("Frame Advance", false);

src/BizHawk.Client.EmuHawk/RetroAchievements/RetroAchievements.cs

@@ -22,6 +22,7 @@ namespace BizHawk.Client.EmuHawk
 		protected IMemoryDomains Domains => Emu.AsMemoryDomains();
 		protected IGameInfo Game => _mainForm.Game;
 		protected IMovieSession MovieSession => _mainForm.MovieSession;
+		protected CheatCollection CheatList => _mainForm.CheatList;
 
 		protected IReadOnlyList<MemFunctions> _memFunctions;