Split helper classes into separate header files

[GavinNL]

There are many helper classes that defined in vulkan.hpp that are potentially useful independent of the vulkan hpp. For example: ArrayProxy<T>, Flags<T>, Result<T>.

It would be nice if these classes/structs were split out into separate header files so they can be used without needing to pull in all of vulkan.hpp

[asuessenbach]

ArrayProxy<T> and Flags<T> could probably be moved into some vulkan_hpp_helper_classes.hpp, or so. But do you mean ResultValue<T> with Result<T>? That class uses vk::Result, which means you would need at least vulkan_enums.hpp as well.