Open shells on virtual terminals for monitoring in interactive mode

We spawn a shell:
- When Bash is first built, on tty2. This shell uses the old Bash,
  so interactive mode needs to be emulated using redirection. Thus,
  entering commands needs to be done using Enter followed by Ctrl+D,
  and certain redirection features are unavailable.
- After moving the system to disk, on tty2. Old Bash, same limitations.
- After 2nd Bash is built, on tty3. This is a fully functional shell.

This is disabled in chroot-like bootstrap modes, or when -i is not set.

steps/improve/open_console.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+# SPDX-FileCopyrightText: 2024 Gábor Stefanik <netrolller.3d@gmail.com>
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+if bash --version | grep -q 'GPLv3'; then
+    env - PATH=${PREFIX}/bin PS1="\w # " openvt -- bash -i
+else
+    bash -c 'while true; do printf "[early Bash - use Ctrl+D] $(pwd) # "; $(cat /dev/tty2); done' &> /dev/tty2 &
+fi

steps/improve/populate_device_nodes.sh

@@ -23,6 +23,8 @@ if mount --version >/dev/null 2>&1; then
 fi
 
 if [ "${CHROOT}" = False ]; then
+    test -c "/dev/tty1" || mknod -m 666 "/dev/tty1" c 4 1
+    test -c "/dev/tty2" || mknod -m 666 "/dev/tty2" c 4 2
     test -c "/dev/console" || mknod -m 666 "/dev/console" c 5 1
     test -b "/dev/sda" || mknod -m 600 "/dev/sda" b 8 0
     test -b "/dev/sda1" || mknod -m 600 "/dev/sda1" b 8 1

steps/manifest

@@ -54,6 +54,9 @@ build: bash-2.05b
 improve: setup_repo
 improve: update_env
 improve: merged_usr
+improve: populate_device_nodes
+define: CONSOLES = ( INTERACTIVE == True && CHROOT == False )
+improve: open_console ( CONSOLES == True )
 build: flex-2.5.11
 build: tcc-0.9.27
 improve: musl_libdir
@@ -80,7 +83,6 @@ build: perl5.004-05
 build: perl5.005-03
 build: perl-5.6.2
 uninstall: perl-5.000 perl-5.003 perl5.004-05 perl5.005-03
-improve: populate_device_nodes
 build: autoconf-2.52
 build: automake-1.6.3
 build: automake-1.6.3
@@ -128,11 +130,13 @@ jump: linux ( CHROOT == False )
 jump: move_disk ( KERNEL_BOOTSTRAP == True )
 improve: finalize_job_count
 improve: finalize_fhs
+improve: open_console ( CONSOLES == True )
 improve: swap ( SWAP_SIZE != 0 )
 build: musl-1.2.4
 build: curl-8.5.0
 improve: get_network ( CHROOT == False )
 build: bash-5.2.15
+improve: open_console ( CONSOLES == True )
 build: xz-5.4.1
 build: file-5.44
 build: libtool-2.4.7