The directory diffing phase in the VersionVault client exists in order to properly get change type and metadata for added, deleted, or renamed files. This was hitting problems with added or deleted directories, adding them as additional changed files. These would then get added to the diff with garbage diff content and bad paths. This change updates the directory diffing to only add things to the file list if they are actually files. Testing Done: Set up a UCM activity with added, nested directories. Saw that the resulting `rbt diff` output only included the changed files.