pub fn compute_rename_map(
) -> (BTreeMap<ParsedFilename, String>, Vec<String>)
Compute the rename map. This is a mapping from original file name to the name it would rename the file in the next step. It avoids unnecessary renames (oldname == newname).
pf_list: All files obtained by
It returns a tuple with the rename map (old name to new name) and files that do not need a rename.