`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>
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