Add functionality to recursively walk a directory to the C_FileSystem API

[rdw-software]

Leftover from #39. I don't need this right now, but it would be nice to have.

Proposed API: C_FileSystem.WalkDirectory(path) - maybe just Walk(path) would be fine, too?

When using ScanDirectory, the resulting table already contains a flag indicating whether an entry can be walked (is a directory). Format of the table: someFolder = true and someFile = false for any given file or folder in the scanned directory. Can then use the path library to resolve paths?