krb5: Unify function to create ccache files
    
    Only 2 types (FILE and DIR) need to precreate files or directories
    on the file system, and the 2 functions were basically identical.
    
    Consolidate all in one common function and use that function directly
    where needed instead of using indirection.
    
    Resolves:
    https://fedorahosted.org/sssd/ticket/2061