Switch qemu sound device from hda-duplex to hda-output

See merge request redox-os/redox!1370

hda-duplex allows recording too. At least for XFCE this results in a
scary mic recording icon even when nothing inside the VM is actually
recording anything.

Two minor build system cleanups

See merge request redox-os/redox!1369

This should be a bit faster.

Fix building and running for the server-minimal config

See merge request redox-os/redox!1368

It doesn't get built

64MB is no longer enough

Without it building fails

Add nushell to demo and ci configs

See merge request redox-os/redox!1367