Add IPv6 ingress security group rules

[mschfh]

what

• Added IPv6 support for ingress security groups
• Added variable validation for http_ingress_cidr_blocks and https_ingress_cidr_blocks
• Added variable validation for ip_address_type
• Updated the http_ingress_cidr_blocks and https_ingress_cidr_blocks defaults values to include ::/0

why

The current implementation only configures IPv4 security group rules, causing IPv6 traffic to be dropped by default for dualstack ALBs

references

AWS Load Balancer dual-stack mode: https://docs.aws.amazon.com/elasticloadbalancing/latest/application/application-load-balancers.html#ip-address-type
AWS Security Group IPv6 support: https://docs.aws.amazon.com/vpc/latest/userguide/security-group-rules.html#security-group-rule-syntax
TF aws_security_group_rule resource: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/security_group_rule#ipv6_cidr_blocks

[GabisCampana]

@Nuru

[mergify]

💥 This pull request now has conflicts. Could you fix it @mschfh? 🙏

[mschfh]

rebased (there is an unrelated docs change, see #187 (comment))

[Nuru]

/terratest

[github-actions]

These changes were released in v1.12.0.