Resolve CFN pseudo parameter references

[abhi7cr]

Description of changes

Resolve CFN pseudo parameter references, e.g. AWS::StackName. This is needed since Gen1 Bucket name has a Ref on the Gen 1 StackName and needs to be resolved prior to moving it to Gen2 stack.

Description of how you validated changes

unit tests

Checklist

• [x] PR description included
• [x] yarn test passes
• [x] Tests are changed or added
• [ ] Relevant documentation is changed or added (and PR referenced)
• [ ] New AWS SDK calls or CloudFormation actions have been added to relevant test and service IAM policies
• [ ] Pull request labels are added

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