Now that we have most of core free of shadowing, we can enable the
warning as an error to catch anything that may be remaining and also
eliminate this class of logic bug entirely.
When writing VFS, it initally seemed useful to include a function to in-place convert container files into directories in one homogenous directory structure, but re-evaluating it now there have been plenty of chances to use it and there has always been a better way. Removing as it is unused and likely will not be used.
Given these are only added to the class to allow those functions to
access the private constructor, it's a better approach to just make them
static functions in the interface, to make the dependency explicit.
