Don't include core/io/image.h in core/os/os.h

`core/os/os.h` doesn't use `core/io/image.h`. It just brings
transitive dependencies. Lots of dependencies because `core/os/os.h`
is transitively included in almost every file of godot

Also added `core/io/image.h` into files^1 where `Ref<Image>` and `core/os/os.h`
were used to prevent obscure errors involving `Ref<Image>`

^1 except those which include `core/io/image_loader.h` or `core/io/image.h` by
corresponding .h file with the same name

Signed-off-by: Yevhen Babiichuk (DustDFG) <dfgdust@gmail.com>
Co-authored-by: A Thousand Ships <96648715+AThousandShips@users.noreply.github.com>

platform/windows/display_server_windows.h

@@ -38,6 +38,7 @@
 
 #include "core/config/project_settings.h"
 #include "core/input/input.h"
+#include "core/io/image.h"
 #include "core/os/os.h"
 #include "drivers/unix/ip_unix.h"
 #include "drivers/wasapi/audio_driver_wasapi.h"