This formats all copyright comments according to SPDX formatting guidelines.
Additionally, this resolves the remaining GPLv2 only licensed files by relicensing them to GPLv2.0-or-later.
Move surface initialization code to a separate file. It's unlikely to
use this code outside of Vulkan, but keeping platform-specific code
(Win32, Xlib, Wayland) in its own translation unit keeps things cleaner.