[KNewFileMenu] Don't emit fileCreated when creating a directory
Summary: BUG: 403100
Test Plan: unit tests pass.
Reviewers: ngraham, hein
Reviewed By: ngraham, hein
Subscribers: kde-frameworks-devel, dfaure
Tags: Frameworks
Differential Revision: https://phabricator.kde.org/D18187
(cherry picked from commit 28dacfe0737515153e0e40dacd7457b7a4840b29)