CLSA-2026-1792570553 dovecot: Fix of 7 CVEs

CVE-2026-27852: bound the transient RFC 2231 parameter list and the MIME parameter budget so a single oversized Content-Type header cannot exhaust imap memory - CVE-2026-33263: track SMTP server connection closure so submission-login does not keep using a closed connection - CVE-2026-33605: fix...