Support scripts in subfolders

[AsaMitakaIT]

I hope to configure scripts for my family through a shared folder, as they do not understand any technical details of Tampermonkey. If this feature is supported, I can remotely add, update, or delete scripts.
Additionally, I think users who have a lot of scripts that need to be categorized and organized will also like it.

[ACTCD]

Duplicate of #398 (comment)

Personally, I don't like the idea of "remote control and implanted scripts", even if it's a family member or friend.

Once we iron out some of the kinks, I think using filename collation will be sufficient for most users.

I wouldn't give the feature any priority at the moment, we still have a lot of heavy core refactoring work ahead of us.