Support AWS Oversize handling for default WAF rules

[cturner-pulsion]

The default disable introspection rule is non compliant with a recent WAF change which makes the OversizeHandling property required.

AWS issued a warning email that after March 31 2023, any updates to WAF Web ACL's without oversize handling, will fail.

In the meanwhile, I have been able to workaround the limitation by defining a new rule manually

    wafConfig:
      enabled: true
      rules:
        - name: "DisableIntrospection"
          priority: 200
          action: Block
          statement:
            ByteMatchStatement:
              FieldToMatch:
                Body:
                  OversizeHandling: "CONTINUE"
              PositionalConstraint: "CONTAINS"
              SearchString: "__schema"
              TextTransformations:
                - Type: "COMPRESS_WHITE_SPACE"
                  Priority: 0

Ideally it would be possible to provide an oversize handling like can be done with Name and Priority. However, a default of "Continue" can be applied in line with the AWS default.

https://docs.aws.amazon.com/waf/latest/developerguide/waf-rule-statement-oversize-handling.html