Improved default values in Edit New File and View File dialogs
Use current file name as a selected default in the dialogs.
This is a Total Commander behavior and it's proved to be useful.
I could not find any case where FileSystem::ensureTrailingSlash
is actually needed.
FIXED: [ 282069 ] Bad default in the New Text File dialog
BUG: 282069
Differential Revision: https://phabricator.kde.org/D13671
(cherry picked from commit e85741cb8823bd7380d985100df501ac82a240ae)