Order GPUs and make selectable.

[takev]

os_settings should return a list of GPUs on the system in the preferred order.

the gfx_device::score() function should still be used to disqualify.

user_settings should include a setting for the selected GPU if it was not the first in preferred order. The setting should be called hiko_display_adapter and it should be the UUID of the adapter that that is selected.

On win32 IDXGIFactory::EnumAdapters is used to list the adapters on the computer, the first adapter corresponding to the primary display is at index 0. see:
https://learn.microsoft.com/en-gb/windows/win32/api/dxgi/nf-dxgi-idxgifactory-enumadapters?redirectedfrom=MSDN

There is a call to get a UUID for these listed adapters, that will correspond with one of the Vulkan UUID of its list of adapters.