[kernel] Use himem.sys method to enable A20 for greater 8042 compatibility - #2798

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@v4, actions/checkout@v2, actions/upload-artifact@v4, open-watcom/setup-watcom@v0. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/