autotests: Fix testXkb in Qt 6 build
The mapping between XKB_KEY_XF86MyComputer and Qt::Key_Launch0 has been fixed in qt 6, so we need to adjust the test.
keySymQt and keySymX were reordered so it's easier to read. Mapping from XKB key to Qt key is easier to understand than Qt key to XKB key; if you want to review this MR, review individual commits
Edited by Vlad Zahorodnii