Enable AutoErrorHandling for rename job

Summary:
If a rename job started from View Mode fails, no warning message is
shown. This is caused by the default disabled `AutoErrorHandling` in
`KJobUiDelegate`.
This patch enables the flag after creating the job.

BUG: 395890
FIXED-IN: 18.04.3

Test Plan:
# Open Gwenview in View Mode
# Try to rename image to already existing filename
# An error message should be displayed

Reviewers: #gwenview, rkflx

Reviewed By: #gwenview, rkflx

Subscribers: rkflx

Differential Revision: https://phabricator.kde.org/D13754