Qt6: Update to 6.6.1

As a patch release, Qt 6.6.1 does not introduce any new features but
contains more than 400 bug fixes, security updates, and other
improvements to the top of the Qt 6.6.0 release. See more information
about the most important changes and bug fixes from the Qt 6.6.1 release
note.

To allow building www/qt6-webengine without CUPS, a CUPS option has been
added and the Pdf module has been split out to a new port: print/qt6-pdf.
This also allows building devel/py-qt6-pyqt without pulling in the unused
WebEngine module. Fixes [1].

Remove a lot of unused dependencies. Fixes [2]. Also remove inconsistent
WWW lines from the individual Makefiles as WWW is alreay defined in
Mk/Uses/qt-dist.mk. [3]

Announcement: https://www.qt.io/blog/qt-6.6.1-released
Rel note: https://code.qt.io/cgit/qt/qtreleasenotes.git/about/qt/6.6.1/release-note.md

PR: 271111 [1], 268692 [2]
Reported by: echoxxzz <echoxxzz@gmail.com> [1],

		Matthieu Volat <mazhe@alkumuna.eu> [2],
		lwhsu (via #freebsd-desktop IRC) [3]

MFH: 2023Q4
Security: 6d9c6aae-5eb1-11ee-8290-a8a1599412c6,

		07ee8c14-68f1-11ee-8290-a8a1599412c6,
		a1e27775-7a61-11ee-8290-a8a1599412c6,
		0da4db89-84bf-11ee-8290-a8a1599412c6