Port Kickoff to shared view component using single-MouseArea pattern
- Moves MouseArea out of the item delegate and uses a single MouseArea per view.
- Ports all the pages to using a shared view component.
Aside from saving a lot of QObjects, using a single MouseArea also
has the advantage that MouseArea.positionChanged isn't fired when
QQuickWindow synthesizes a hover event per frame, unlike MouseArea
.containsMouse. This fixes a user-reported bug in the search page,
and the same pattern is used by various other UIs we have for
Reviewers: Plasma, ngraham, davidedmundson
Reviewed By: Plasma, davidedmundson
Subscribers: davidedmundson, ngraham, plasma-devel
Differential Revision: https://phabricator.kde.org/D15855