Update hidden state correctly
Summary:
When renaming a file from '.hidden' to 'not_hidden', the file
would still be displayed like a hidden file with a semi-transparent
icon and a grey text.
BUG: 399599
Reviewers: Dolphin, elvisangelaccio
Reviewed By: elvisangelaccio
Subscribers: elvisangelaccio, kfm-devel
Tags: Dolphin
Differential Revision: https://phabricator.kde.org/D16115