databases/kbibtex: Remove www/qt5-webkit reference

Make the WEBENGINE option default for aarch64, as well, since
www/qt5-webengine builds on it and www/qt5-webkit is no longer in
the ports tree to use an alternative.

While here, add LICENSE and remove many other unused dependencies.

MFH: 2024Q1
(cherry picked from commit 3106e8f4d8022f219435ce4a941c8610bd4e56bc)