x11-toolkits/qt6-declarative: Install Qt6QuickTools

This fixes pkg-plist issues for users that build on live systems if
graphics/qt6-svg is already installed.

While here, fix configure if sysutils/lttng-ust is installed.

https://lists.freebsd.org/archives/freebsd-ports/2024-August/006545.html

Reported by: Tatsuki Makino <tatsuki_makino_at_hotmail.com>
MFH: 2024Q3