Add retroarch for 32bit architecture

# Proposed x86 package names Suggested packaged names for x86 AppImages from https://buildbot.libretro.com/ : * retroarch-x86 * retroarch-qt-x86 * retroarch-nightly-x86 - https://buildbot.libretro.com/nightly/linux/x86/RetroArch.7z * retroarch-qt-nightly-x86 - https://buildbot.libretro.com/nightly/linux/x86/RetroArch_Qt.7z Code for x86_64 RetroArch AppImages can be [reused](https://github.com/search?q=repo%3Aivan-hc%2FAM%20retroarch&type=code). This will complement: * https://github.com/ivan-hc/AM/issues/2255 Thank you very much for your endless efforts on AM and for continuously improving the project! 🙏🐉