Introduce NameFinderJob that suggests new "New Folder" names
This is the younger brother of KFileUtils::suggestName(), the major difference is that it's async as it uses a StatJob internally, which also means it works for both local and remote filesystems.
NameFinderJob is modelled after OpenUrlJob.
Thanks to sitter and dfaure for the API design (see !153 (merged)).
Edited by Ahmad Samir