graphics-hook: Fix crash with Vulkan DirectDisplay

[mbechard]

Vulkan Direct Display uses extensions:
VK_KHR_display/VK_EXT_direct_mode_display
This workflow allows creating swapchains that arn't active on the desktop, so they don't have HWNDs.
Avoid trying to create swap_data when a HWND can't be found.

Fixes #11581

Description

VK_KHR_display/VK_EXT_direct_mode_display extensions created swapchains without HWND handles.
Avoid trying to work with HWND when they can't be found.

Motivation and Context

The old behavior causes crashes when applications using Direct Display.

How Has This Been Tested?

The only thing I tested was that the crash doesn't occur. If avoiding filling the swap_data has
greater ramifications, then I'll need feedback from devs more familiar with OBS.

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[jjulianoatnv]

This change makes sense. Not every VkSurfaceKHR/VkSwapchainKHR is associated with an hwnd. Assuming there is an associated hwnd results in undefined behavior (possibly application crash.)

The only caller of add_surf_data() is OBS_CreateWin32SurfaceKHR(). When a VkSurfaceKHR is created using a Vulkan command other than VkCreateWin32SurfaceKHR, then add_surf_data is not called for that surface. vkCreateDisplayPlaneSurfaceKHR() is one example of an alternate way to create a surface. There might be additional ways to create a surface.

The proposed change adds defense against both of the following fallacies:

• It is a flaw to assume that all methods of creating a surface are wrapped by the win-capture plugin.
• It is a flaw to assume that all methods of creating a surface associate the surface with an hwnd.