feat: automate preprocessing steps for refactor

[abhi7cr]

Description of changes

Automate the first 2 steps of template gen prior to refactor by executing updateStack on behalf of the customers:

1. Resolving refs, conditions and dependencies in Gen1 stack
2. Removing dummy resource in Gen2 stack

Note: Haven't changed the command name (execute) yet. Will be part of another PR.

Issue #, if available

Description of how you validated changes

Ran the template gen command locally.

Checklist

• PR description included
• yarn test passes
• 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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