[PFR] Create reference URL egress filtering add-on

[jonrau1]

Story As a user of SyntheticSun I want to have a URL filtering solution as an add-on so that I can utilized existing threat intel and automation infrastructure to provide protection against outbound communications to known malicious destinations.

Definition of Done

• Squid used for URL filtering, added in Appendix B
• Automation and configuration management scripts created to periodically update lists of malicious domains / URLs
• CloudFormation support for a new reference VPC using the solution
• Auto-scaled + load balanced Proxies
• Onboard Squid logs into SyntheticSun core solution
• Updated documentation

Nice to Have

• Fargate Services are used for Squid
• Multi-VPC egress pattern implemented via TGW

Additional Information

• https://hub.docker.com/r/sameersbn/squid/
• http://www.squid-cache.org/Doc/
• https://aws.amazon.com/blogs/security/how-to-add-dns-filtering-to-your-nat-instance-with-squid/
• https://aws.amazon.com/blogs/security/how-to-set-up-an-outbound-vpc-proxy-with-domain-whitelisting-and-content-filtering/
• https://aws.amazon.com/blogs/networking-and-content-delivery/how-to-use-aws-privatelink-to-secure-and-scale-web-filtering-using-explicit-proxy/