Add "Create New" menu to "Control" button

Summary: Right now, the "Create New" menu's functionality is not visible with Dolphin's default layout that has a Control button instead of a menubar. This patch adds that functionality to the Control button's menu so that it's actually discoverable for regular users.

Test Plan:

All menu items work.

Reviewers: Dolphin, broulik, elvisangelaccio

Reviewed By: Dolphin, elvisangelaccio

Subscribers: acrouthamel, anthonyfieroni, elvisangelaccio, kfm-devel

Tags: Dolphin

Differential Revision: https://phabricator.kde.org/D15609