make_console_stdio() forces KD_TEXT while reopening /dev/console. When
systemd-shutdown enters the exitrd, this can expose the text console over
a retained graphical shutdown splash.
Let callers choose whether to switch to text mode, and preserve the mode
for the exitrd handoff. Keep the existing text-mode behavior for manager
reexecution and the crash shell. Restore text mode if executing /shutdown
fails and before reporting a fatal error and freezing.
Add an unsafe, nonparallel virtual-console regression test requiring
explicit opt-in and an already-owned inactive VT in a disposable VM.
Check graphics preservation and text restoration through a private
/dev/console bind mount, retain stderr diagnostics, and restore the saved
mode in the parent even if the child fails.
