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>