Add a machine abstraction to LumaCore, with QEMU as its first
backend: templates mirroring frida-core's test guests, a QMP client,
and a display that maps QEMU's surface over D-Bus rather than
copying frames.
Leave readiness to the user: drive the guest, mark it ready, and come
back to that snapshot later. Keep the machine in the project, so
booting it again resumes where it was marked. Hand the stub to
addBareboneDevice, so it joins the picker beside the other devices.
Show the display while booting, and afterwards in a Machines panel,
which the side panel now models as an enum to share its slot.
Ole André Vadla Ravnås