normalize path for SVF Downloader

[lucaschadwicklam97]

When using the downloader via APS VS Code extension, the downloader downloads corrupt files with filenames that match objects_*.json.gz. From a manifest.json file retrieved from unzipping contents from the .svf file, the asset URI's for those objects include \..\ in the path, which, when normalized, will go up the directory, and thereby download the correct contents for the file.

I've tested this with Python and the files outputted after the normalizing the path are valid JSON and no longer corrupt.

[lucaschadwicklam97]

hi @petrbroz, would you be able to review this? let me know if you need anything else from me

[petrbroz]

Thanks @lucaschadwicklam97, good catch! I'm surprised I haven't run into this issue before (the objects_*.json.gz would always download fine for me), but this code change looks like it would help in these kinds of scenarios.