KRun: allow executing "add network folder" without confirmation prompt

Summary:
Dolphin enables the KRun feature of asking before executing shell
scripts and desktop files (not really for security reasons, but more to
avoid users executing scripts by mistake, I think).
However kio_remote's "add network folder" doesn't look like a desktop
file, but more like a builtin feature, it's weird to ask confirmation
for this one.

Test Plan: dolphin remote:/, click on "add network folder", no prompt anymore

Reviewers: mwolff, dhaumann

Reviewed By: mwolff

Subscribers: elvisangelaccio, ngraham, Dolphin, Frameworks

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D10172