ResizeStrategy.apply() - don't consume the input size
ResizeStrategy.apply() - don't consume the input size

And remove an awkward way of copying the natural_size in the Converter.

Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/669>

GNOME/librsvg,GNOME/librsvg,GNOME/librsvg,GNOME/librsvg