Be explicit about special menu item roles, required to prevent menu items from missing on OSX
Summary: Work around a problem discussed here https://forum.qt.io/topic/45963/menu-actions-and-textheuristicrole-on-os-x/3
Test Plan: Verify 'Configure Launches', 'Configure Selection', 'About Kdevelop Platform', 'quit' (session) menu items are present on OSX.
Reviewers: mwolff, kfunk, KDevelop
Reviewed By: kfunk, KDevelop
Subscribers: kdevelop-devel
Projects: KDevelop
Differential Revision: https://phabricator.kde.org/D625