If some folder was renamed while `baloo_file` was not running, it should pop up in `UnIndexedFileIterator`.
However, it does not, because previously it was thought that folder should never be reindexed.
It is not correct: it should be reindexed if its name was changed.
As a consequence, we end up with invalid entries inside DB (DocumentUrl is invalid).
Also, added unit test for `UnIndexedFileIterator`, which covers basic cases (including this one).
Right now it fails due to {D21427} (one of the folders has trailing slash, while it should not)
Also, since we need to check if name was changed already inside iterator, we can export this information
and reuse it from `UnindexedFileIndexer`.