Save the IMAP mailbox list in the backup

The mailbox list is needed to quickly find an IMAP folder path inside
a given backup snapshot. Maildir path-encoding format can be obtained
with the "doveadm mailbox path" command.

imageroot/bin/module-cleanup-state

@@ -7,4 +7,5 @@
 
 echo "Cleaning up Mail state:"
 rm -vf pcdb-dump.sql
+rm -vf maildir-dump.lst
 rm -vf *.is-enabled

imageroot/bin/module-dump-state

@@ -7,6 +7,11 @@
 
 echo "Dumping Mail state to disk:"
 podman exec postfix sqlite3 /srv/pcdb.sqlite .dump > pcdb-dump.sql
+echo "Saving Maildir IMAP folder index:"
+podman exec -i dovecot ash -s >maildir-dump.lst <<'EOF'
+doveadm -f tab mailbox list -A | tail -n +2 | grep -v -E $'\t''(Shared|Public)(/|$)'
+EOF
+echo "Saving service status:"
 for unit in clamav.service freshclam.timer; do
     systemctl --user is-enabled "${unit}" > "${unit}".is-enabled || : # ignore exit code
 done

imageroot/etc/state-include.conf

@@ -4,6 +4,7 @@
 # Restic --files-from: https://restic.readthedocs.io/en/stable/040_backup.html#including-files
 #
 state/pcdb-dump.sql
+state/maildir-dump.lst
 state/dovecot.env
 state/rspamd.env
 state/*.is-enabled