[Vulkan] Crash if vulkan render plugin is preloaded

[Meetem]

It seems like this line in Hook_vkGetInstanceProcAddr should return vkGetInstanceProcAddr(device, funcName); instead of NULL
Because will NULL return editor is crashing on start, and no initialization is done.

NativeRenderingPlugin/PluginSource/source/RenderAPI_Vulkan.cpp

Line 115 in d6d6f99

static VKAPI_ATTR PFN_vkVoidFunction VKAPI_CALL Hook_vkGetInstanceProcAddr(VkInstance device, const char* funcName)

[Meetem]

Also in example plugin it seems like RenderAPI_Vulkan_OnPluginLoad is never called.

[KsGin]

this patch will fix it #23