
Implements Conntrack Helper service plugin for conntrack helper resources. Supports create, update and delete conntrack helper for l3 routers. A new configuration option: [l3-conntrack-helpers]/allowed_conntrack_helpers introduced to allow the operator to configure CT helpers, and the helper protocol constraints. Related-Bug: #1823633 Depends-On: https://review.opendev.org/663446 Change-Id: I58193955261f50b18b1946261fe662da6b20f0f5