enhancement: Improve the backup script

- Significantly decrease time it takes to save a backup
- Remove host dependency on 'zip' binary
- Preserve file attributes on backed-up files
- Avoid copying files on the pi itself to /tmp

Signed-off-by: Jeremy O'Brien <neutral@fastmail.com>

scripts/restore.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+
+# name of the ethernet gadget interface on the host
+UNIT_HOSTNAME=${1:-10.0.0.2}
+# output backup zip file
+BACKUP=${2:-pwnagotchi-backup.tgz}
+# username to use for ssh
+USERNAME=${3:-pi}
+
+ping -c 1 "${UNIT_HOSTNAME}" >/dev/null || {
+  echo "@ unit ${UNIT_HOSTNAME} can't be reached, make sure it's connected and a static IP assigned to the USB interface."
+  exit 1
+}
+
+echo "@ restoring $BACKUP to $UNIT_HOSTNAME ..."
+cat ${BACKUP} | ssh "${USERNAME}@${UNIT_HOSTNAME}" "sudo tar xzv -C /"