Make vk-bootstrap capable of loading the vulkan runtime and not need to
link against the library. This improves the usability of vk-bootstrap since
now you don't need the vulkan library on your system to build.
This commit also changes how SystemInfo works so as to allow the dynamic
vulkan loading.
Now there is a concise example of the library in use all the way to presenting.
Needs to be rewritten to remove exceptions, but for first pass its good enough.
