sftp: map sftp_open error to kio error
Summary:
sftp gives out more relevant errors such as SSH_FX_PERMISSION_DENIED,
let's forward them as KIO errors instead of using the general cannot open
error.
Test Plan: hoping for the best! bad permissions on the remote now actually raise suitable kio errors, functionally that seems to make little difference unfortunately
Reviewers: feverfew
Reviewed By: feverfew
Subscribers: kde-frameworks-devel, kfm-devel
Tags: Dolphin, Frameworks
Differential Revision: https://phabricator.kde.org/D29743