[Request] Strongswan

Would love to see a professional docker image for StrongSwan (GitHub - strongswan/strongswan: strongSwan - IPsec-based VPN).

StrongSwan is a well-known IPSec Tunnel solution without an official docker image and community ones are not up-to-date or necessarily optimized.

Loving other images by linuxserver.io so far, thanks for the awesome work!