fix(options): Prevent crash when Advanced Display window is missing

[sentry]

This PR addresses a fatal EXCEPTION_ACCESS_VIOLATION_READ crash (CLIENT-580) that occurred when opening the Options Menu.

Root Cause:
The OptionsMenuInit function, along with showAdvancedOptions, acceptAdvancedOptions, and cancelAdvancedOptions, would attempt to call winHide(TRUE) on the WinAdvancedDisplay GameWindow pointer without first checking if the pointer was valid. WinAdvancedDisplay could be null if TheWindowManager->winGetWindowFromId(nullptr, "OptionsMenu.wnd:WinAdvancedDisplayOptions") failed to find the specified window in the loaded UI layout (e.g., due to a modified or incomplete OptionsMenu.wnd file).

Fix:
Added null checks for WinAdvancedDisplay before any calls to winHide in:

• Generals/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/OptionsMenu.cpp
• GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/OptionsMenu.cpp

This ensures that if the WinAdvancedDisplayOptions window is not found in the UI layout, the game will no longer crash, and the Options Menu will simply open without the advanced display panel.

Fixes CLIENT-580

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