VulkanRenderer: implement metal view

The metal view backing the MoltenVK compatibility wrapper is written in
Obj-C.

It would have been possible to use the Objective-C runtime in C++ but
the code is less performant (the symbol binding is done at first use
instead of the beginning of the program) and actually harder to get
right.

Note that MoltenVK is not linked to the loader, so the libMoltenVK.dylib
object must be available for loading.

include/Nazara/VulkanRenderer/Wrapper/Surface.inl

@@ -140,6 +140,27 @@ namespace Nz
 		}
 		#endif
 
+		#ifdef VK_USE_PLATFORM_METAL_EXT
+		inline bool Surface::Create(const VkMetalSurfaceCreateInfoEXT& createInfo, const VkAllocationCallbacks* allocator)
+		{
+			m_lastErrorCode = m_instance.vkCreateMetalSurfaceEXT(m_instance, &createInfo, allocator, &m_surface);
+			return Create(allocator);
+		}
+
+		inline bool Surface::Create(id layer, const VkAllocationCallbacks* allocator)
+		{
+			VkMetalSurfaceCreateInfoEXT createInfo =
+			{
+				VK_STRUCTURE_TYPE_METAL_SURFACE_CREATE_INFO_EXT,
+				nullptr,
+				0,
+				layer
+			};
+
+			return Create(createInfo, allocator);
+		}
+		#endif
+
 		inline void Surface::Destroy()
 		{
 			if (m_surface != VK_NULL_HANDLE)
@@ -262,6 +283,10 @@ namespace Nz
 				return true;
 #endif
 
+#ifdef VK_USE_PLATFORM_METAL_EXT
+			if (instance.IsExtensionLoaded(VK_EXT_METAL_SURFACE_EXTENSION_NAME))
+				return true;
+#endif
 			return false;
 		}