feature(waf): add support for WAF V2 logging and sampling

[rmartin48]

Resolves https://github.com/DNXLabs/terraform-aws-ecs/issues/35

Adding support for WAFv2 logging and sampling for the ALB. It is important get detailed information about traffic that is analysed by the WAF web ACLs in order to evaluate the rules groups and make improvements.

Types of changes

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• [ ] Bugfix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Documentation Update (if none of the other choices apply)

Checklist

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• [x] I have read the CONTRIBUTING.md doc.
• [x] I have added necessary documentation (if appropriate).
• [x] Any dependent changes have been merged and published in downstream modules.

[rmartin48]

Closing this as it is better implement customisation of the WAF in your own terraform config. Particularly when needing things like rule exclusions.