fix : support overrideAction for WAF

[yasuto-nishii]

Fix for #578.

When v1 to v2 migration, overrideAction in WAF code was missed to migrate.

override action is typically None: {}, or Count : {}
https://docs.aws.amazon.com/waf/latest/APIReference/API_OverrideAction.html

I referred around this code in v1 branch.
If overrideAction is set, use overrideAction. Otherwise, Action is used same as before.
https://github.com/sid88in/serverless-appsync-plugin/blob/v1.14.0/src/index.js#L1612

tested with AWS

• cloud formation was generated same as v1
• sls deploy suceeded

      "Name": "AWSManagedRulesCommonRuleSet",
      "Priority": 20,
      "Statement": {
        "ManagedRuleGroupStatement": {
          "VendorName": "AWS",
          "Name": "AWSManagedRulesCommonRuleSet"
        }
      },
      "VisibilityConfig": {
        "CloudWatchMetricsEnabled": true,
        "MetricName": "AWSManagedRulesCommonRuleSet",
        "SampledRequestsEnabled": true
      },
      "OverrideAction": {
        "None": {}
      }
    },

[yasuto-nishii]

@bboure
Hi, to address WAF CFn issue #578, I created PR based on v1 implementation.
https://github.com/sid88in/serverless-appsync-plugin/blob/v1.14.0/src/index.js#L1612

I had tested on my actual AWS env by installing my branch, also I verified jest result is expected one.
Hope this code helps to fix the bug.

[bboure]

Sorry for taking so long to review this, and thanks for this!

I haven't used WAF for a long time, but the changes and explanations look good to me.

You will need to rebase/resolve conflicts though.

[yasuto-nishii]

@bboure
Thanks for reply. I had rebased and resolved the conflict.

[bboure]

Thanks. ! @yasuto-nishii

[ShuLaPy]

Guys this commit is failing the build with the error Property 'overrideAction' does not exist on type 'WafRuleCustom'.. @yasuto-nishii you forgot to add type for rule.