Warn user when using device layers field #1086

Warn user when using device layers field #1086

The device layer fields in VkDeviceCreateInfo are deprecated and have
been for years. Users should not be adding anything to them (and if
they do, it should match the layers added in VkInstanceCreateInfo).

This would be a warning that 'device layers are deprecated, they do
nothing' in case a user is trying to enable validation layers using
them. Charles has seen multiple users not knowing that they are
deprecated and get burned by the API due to not having validation
layers enabled.

Since there may be applications in the wild which currently do provide
a list of layers to device create info, this warning should only be
issued if the list differs from instance creation. That way no spurious
warnings are created.