Expose profile switching through d-bus

Summary:
Change the profile of the running session through d-bus.
This can be useful for scripting the changing of profiles throughout
the day, putting less strain on one's eyes at night and being bright
in the day.

Test Plan:
qdbus $KONSOLE_DBUS_SERVICE $KONSOLE_DBUS_SESSION setProfile Shell

Reviewers: #konsole, hindenburg

Reviewed By: #konsole, hindenburg

Subscribers: konsole-devel

Tags: #konsole

Differential Revision: https://phabricator.kde.org/D13486