OPNSense/core bee9132src/etc/inc/plugins.inc.d ipsec.inc, src/www vpn_ipsec_phase1.php

IPsec: add margintime + rekeyfuzz (https://wiki.strongswan.org/projects/strongswan/wiki/ExpiryRekey), closes https://github.com/opnsense/core/issues/3722

(cherry picked from commit 680bd22980b1e157de14ac3df6b4814aa8d94c85)
DeltaFile
+33-2src/www/vpn_ipsec_phase1.php
+6-0src/etc/inc/plugins.inc.d/ipsec.inc
+39-22 files

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