KDE: It goes to 6!

This megacommit merges all the work from
https://github.com/freebsd/freebsd-ports-kde/tree/kde-it_goes_to_6
Specifically:
- KDE Plasma 6 ports updated to 6.2.5
- KDE Applications ports updated to 24.12.0
- Development ports of KDE Applications removed
- A lot of various ports switched to Qt 6 by default
- Some KDE Frameworks 5 and Plasma 5 ports are adapted to be coinstallable
  with their 6 counterparts

PR:		284351
Exp-run by:	antoine
Pull Request:	https://github.com/freebsd/freebsd-ports/pull/341

Co-authored-by:	Max Brazhnikov <makc@FreeBSD.org>
Co-authored-by:	Kenneth Raplee <kenrap@kennethraplee.com>
Co-authored-by:	Jason E. Hale <jhale@FreeBSD.org>
Co-authored-by:	Gleb Popov <arrowd@FreeBSD.org>

audio/opus: bump consumers after update to 1.4

*: Bump PORTREVISIONs for math/mpc update to 1.3.1

Remove WWW entries moved into port Makefiles

Commit b7f05445c00f has added WWW entries to port Makefiles based on
WWW: lines in pkg-descr files.

This commit removes the WWW: lines of moved-over URLs from these
pkg-descr files.

Approved by:		portmgr (tcberner)

Add WWW entries to port Makefiles

It has been common practice to have one or more URLs at the end of the
ports' pkg-descr files, one per line and prefixed with "WWW:". These
URLs should point at a project website or other relevant resources.

Access to these URLs required processing of the pkg-descr files, and
they have often become stale over time. If more than one such URL was
present in a pkg-descr file, only the first one was tarnsfered into
the port INDEX, but for many ports only the last line did contain the
port specific URL to further information.

There have been several proposals to make a project URL available as
a macro in the ports' Makefiles, over time.

metaport: remove license

metaports do not contain any licensed files, or materials

kde: remove unnecessary comments in CATEGORIES

cleanup: remove transitive py27 deprecation (www/qt5-webengine)

One more small cleanup, forgotten yesterday.
Reported by:	lwhsu

Remove # $FreeBSD$ from Makefiles.

Mark ports recursively depending on Python 2.7 for expiration on June 23.

For ports optionally dependending on Python 2.7, just mark those options
as expired. Remove konquerer from the x11/kde-baseapps metaport and bump
its PORTREVISION.

Submitted by:	rene
Reviewed by:	portmgr, adridg, ehaupt, lme, madpilot, pizzamig, se, sunpoet, yuri
Approved by:	portmgr
Differential Revision:	https://reviews.freebsd.org/D28665

Update KDE Applications to 18.12.2

[1] https://www.kde.org/announcements/announce-applications-18.12.2.php
[2]
https://www.kde.org/announcements/fulllog_applications-aether.php?version=18.12.2

Fix Qt5 symbol version scripts to put the catch-all clause first.  When
a symbol matches multiple clauses the last one takes precedence.  If the
catch-all is last it captures everything.  In the case of Qt5 libraries
this caused all symbols to have a Qt_5 label while some should have
Qt_5_PRIVATE_API.  This only affects lld because GNU ld always gives the
catch-all lowest priority.

Older versions of Qt5Webengine exported some memory allocation symbols from
the bundled Chromium.  Version 5.9 stopped exporting these [1] but the
symbols were kept as weak wrappers for the standard allocation functions to
maintain binary compatibility. [2][3]  The problem is that the call to the
standard function in these weak wrappers is only resolved to the standard
function if there's a call to this standard function in other parts of
Qt5Webengine, because only then is there a non-weak symbol that takes
precedence over the weak one.  If there's no such non-weak symbol the call

Update KDE Applications to 18.08

Changelog: https://www.kde.org/announcements/announce-applications-18.08.0.php

x11/kde5: Pull in the complete plasma5 metaport and not only the desktop.

As this is the "big" meta port for the Qt5-based KDE desktop it makes sense
to pull in every plasma5 component and not just the desktop.

This way, ksshaskpass and so on will also be available, without having to
install them afterwards manually.

Replace bsd.qt.mk by Uses/qt.mk and Uses/qt-dist.mk

From now on, ports that depend on Qt4 will have to set
	USES=		qt:4
	USE_QT=		foo bar
ports depending on Qt5 will use
	USES=		qt:5
	USE_QT=		foo bar

PR:		229225
Exp-run by:	antoine
Reviewed by:	mat
Approved by:	portmgr (antoine)
Differential Revision:	-https://reviews.freebsd.org/D15540

Fix pkg-descr for the kde[45] metaports as well
 - kde4 is legacy
 - kde5 is current (and isn't called KDE5)
 - fix https while I'm at it

Approved by:	tcberner (mentor, implicit)

Correct comment on the two top-level KDE ports:
 - indicate that the KDE4 metaport is legacy
 - there is no KDE5, so don't call it that in the comment even if
   the port *is* named suggestively (for that matter, Software
   Collection was never intended to be used in public communication
   either).

Approved by:	tcberner (mentor, implicit)

Add the KDE metaports

* add multimedia/dragon (was missing)
* add the meta ports for the categories
* add x11/kde5 [yeah, we know, there technically is no "KDE 5"]