Port KRun::run usage to run another Dolphin process, to ApplicationLauncherJob

Test Plan: Opening a new window works

Reviewers: elvisangelaccio, ngraham, meven

Reviewed By: elvisangelaccio, meven

Subscribers: meven, kfm-devel

Tags: #dolphin

Differential Revision: https://phabricator.kde.org/D28807