fix(aws-cdk): fix cdk error on Windows

[Iamz]

Fix an error when running any cdk command on Windows caused by '/' in ts-node path.

Fixes #2657

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Pull Request Checklist

• Testing
  • Unit test added (prefer not to modify an existing test, otherwise, it's probably a breaking change)
  • CLI change?: coordinate update of integration tests with team
  • cdk-init template change?: coordinated update of integration tests with team
  • Manual test on Linux/Windows
    • cd packages/aws-cdk
    • mkdir temp && cd temp
    • ../bin/cdk init --language typescript
    • cdk synth # Resources: {}
• Docs
  • jsdocs: All public APIs documented
  • README: README and/or documentation topic updated
  • Design: For significant features, design document added to design folder
• Title and Description
  • Change type: title prefixed with fix, feat and module name in parens, which will appear in changelog
  • Title: use lower-case and doesn't end with a period
  • Breaking?: last paragraph: "BREAKING CHANGE: <describe what changed + link for details>"
  • Issues: Indicate issues fixed via: "Fixes #xxx" or "Closes #xxx"
• Sensitive Modules (requires 2 PR approvers)
  • IAM Policy Document (in @aws-cdk/aws-iam)
  • EC2 Security Groups and ACLs (in @aws-cdk/aws-ec2)
  • Grant APIs (only if not based on official documentation with a reference)

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license.

[eladb]

Can you please search for all usages of ts-node. I believe this is another one, but just to make sure I didn't forget anything.

[Iamz]

That's the only one I found as well. I'll change that too and push again.