Vulkan: Fix Compilation Issues on Windows

VKVertexAttributeObject was both defined as a class and a struct.
Settled on being a class.

Also removed an assert that is currently failing as workbench has
more attributes defined than actually used.

Pull Request: https://projects.blender.org/blender/blender/pulls/107874

source/blender/gpu/vulkan/vk_vertex_attribute_object.cc

@@ -96,8 +96,6 @@ void VKVertexAttributeObject::update_bindings(const VKContext &context, VKBatch
   }
 
   is_valid = true;
-
-  BLI_assert(interface.enabled_attr_mask_ == occupied_attributes);
 }
 
 void VKVertexAttributeObject::update_bindings(VKImmediate &immediate)

source/blender/gpu/vulkan/vk_vertex_attribute_object.hh

@@ -22,7 +22,8 @@ class VKImmediate;
 
 using AttributeMask = uint16_t;
 
-struct VKVertexAttributeObject {
+class VKVertexAttributeObject {
+public:
   bool is_valid = false;
   VkPipelineVertexInputStateCreateInfo info = {
       VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO, NULL};