yuzu-cmd: Fullscreen Improvements (#6656)

* emu_window_sdl2_vk: Use the generated SDL config

On Linux, due to the way we include SDL2 as a submodule, it makes it
difficult for us to specify which SDL_config.h we intended to include.
Before, CMake would default to the dummy one included with SDL and
ignore the generated one.

This tells CMake to use the generated one. In addition, we define
USING_GENERATED_CONFIG_H to throw an error in case the dummy config is
used by accident. Fixes Vulkan not working on Linux yuzu-cmd.

* emu_window_sdl2_vk: Specify the window manager if it should be supported

The original language "not implemented" is wrong if the implementation
exists but is not compiled. This causes a bit of a debugging headache
when it goes wrong. Log it if the window manager is known before
exiting.

* sdl_impl, emu_window: Remove clang ignore

Fixed upstream by
libsdl-org/SDL@25fc40b0bd44c484051064bc6b945ea9943f88dd

* Enable fullscreen support for Vulkan on yuzu-cmd

Hooked up the existing SDL2 logic for fullscreen support in the Vulkan window of yuzu-cmd.

* Change fullscreen logic to attempt desktop resolution first on yuzu-cmd

Changed the order in which we attempt to switch to fullscreen. First try desktop resolution first, if it fails fall back to streched fullscreen using windowed resolution.

Co-authored-by: lat9nq <22451773+lat9nq@users.noreply.github.com>
Co-authored-by: san <san+gitkraken@smederijmerlijn.nl>