A web browser engine not being available should not cause the whole UI to become unavailable, especially when not required for the UI itself to work. Move packages depending on qt6-qtwebengine to a separate subpackage, that gets pulled only on arches where qtwebengine is available. Signed-off-by: Ferass El Hafidi <funderscore@postmarketos.org> Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/8373>