Do not limit mouse actions to titleBarArea but allow on complete titleBarPosition

Summary:
Mouse actions like wheel and double click were restricted to the titleBar
area. This made the top most pixel non-interactive as it's not part of the
titleBarArea.

This change makes the complete titlebarPosition interactive. That is it
includes for a "normal" (top) setup also the TopLeft/Top/Right section.
Thus the top most pixel can be double clicked, mouse wheeled, etc.

For the Wayland case the test case is adjusted.

BUG: 362860
FIXED-IN: 5.7.0

Reviewers: Plasma

Subscribers: plasma-devel

Projects: Plasma

Differential Revision: https://phabricator.kde.org/D1596