Parse all tests

[Nashtare]

This PR adds an extra flattening step pre test parsing to accommodate for the particular structure of the Shanghai and VMTests folders.

@BGluth Not sure my approach is super clean, hence welcoming feedback more than ever! 😅

closes #33

[Nashtare]

Note that clippy recommends using PermissionsExt, as set_readonly(false) leads to a file that is wold writeable, though I haven't been able to fix the writing rights with PermissionsExt, I suspect it may be coming from the user's umask messing up permissions?

[BGluth]

Yeah I think your approach is good!

My unfinished attempt involved adjusting the logic in fs_scaffolding.rs to drill down into sub-directories until we found directories with just .json files, but your approach is actually looking a bit cleaner than mine.

I'm not getting the clippy warnings you were getting for whatever reason though, so I'm not sure what's up with that. It seems to run fine if I get rid of the write permission logic that you added, but if it was causing an issue on your end I'm fine to leave it in (as it might cause issues for someone else).

[Nashtare]

Hmm yeah I couldn't copy the files in the subfolders without changing the writing permissions, not sure what's the underlying cause if you're not getting this on your end..

[BGluth]

Regardless I'm good to merge. Don't feel like you need to dig too deep into the cause if it's going to be a time sink on your end. 👍