Add support for QSurface::VulkanSurface and QVulkanWindow.
Usage:
1) Build MoltenVK according to instructions
2) Configure Qt: ./configure -I /path/to/MoltenVK/Package/Release/MoltenVK/include
3) export QT_VULKAN_LIB=/path/to/MoltenVK/Package/Release/MoltenVK/macOS/libMoltenVK.
Implement support for QSurface::VulkanSurface by enabling
layer mode for QNSView and then creating a CAMetalLayer,
which the MoltenVK translation layer can run on.
MoltenVK provides an implementation of the Vulcan API,
which means that the platform integration is similar
to other platforms: implement a QCocoaVulkanInstance
where we pass the QNSView instance to the vkCreateMacOSSurfaceMVK
Vulkan surface constructor function.
Using Vulkan directly without QVulkanWindow is possible, but not
tested.
We currently load libMoltenVK at run-time and use the
existing QT_VULKAN_LIB environment variable to set its
path. For deployment purposes it would be better to
link against MoltenVK.frameworkm, but this
Task-number: QTBUG-66966
Change-Id: I04ec6289c40b199dca9fed32902b5d2ad4e9c030
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>