Refactor the framebuffer type so that it encapsulates a single framebuffer
Refactor the framebuffer type so that it encapsulates a single framebuffer

This is continuing the pattern of having collections of types that encapsulate a
single raw Vulkan object, rather than single object that encapsulates multiple
raw vulkan objects.

StrayLightning/aeolius,StrayLightning/aeolius,StrayLightning/aeolius