Fix #104723: Freestyle SVG output ensure path exists

Previously Freestyle SVG exporter does not ensure path exists, this would
lead to crashe after rendering. Now fixed.

This was also reported in blender main repo, for simpler process I'll
just link it here:
https://projects.blender.org/blender/blender/issues/111028

Pull Request: https://projects.blender.org/blender/blender-addons/pulls/104832