kkeyserver: use new XF86keysym.h & qxcbcommon.cpp
Include the latest XF86keysym.h. Update the key mappings to match the latest qxcbcommon.cpp in Qt6.
kkeyserver: add api for Qt Key mapping to multiple X Keys
Upstream approved and merged https://codereview.qt-project.org/c/qt/qtbase/+/535951, which modifies qxcbcommon.cpp, making Qt::Key_Calculator correspond to both XF86Calculator & XF86Calculater.
Edited by Yifan Zhu