Fix imports for several built-in QML modules

Summary:
This patch adds several missing special cases for QML modules that
previously were not found correctly. The additional unit test
ensures that the paths are really found and should work on a standard
CI system with recent Qt.

Test Plan: added unit test and now it passes

Reviewers: brauch, mwolff, KDevelop, apol, kfunk

Reviewed By: KDevelop, apol, kfunk

Subscribers: apol, kdevelop-devel

Differential Revision: https://phabricator.kde.org/D1634