fix(cfn2ts): properly deTokenize string[]

[rix0rrr]

Because of accepted Tokenized values, cfn2ts previously translated a
string and string array into:

interface Props {
    someString: string;
    stringArray: Array<string | Token> | Token;
}

The latter was not intended. We now emit:

interface Props {
    someString: string;
    stringArray: string[];
}

Since the Token will be typed as Object in Java, this change now makes
it impossible to mistakenly pass any old java Object. A typical case
would be pass a Subnet where a string subnetId was expected, failing
in a nonobvious way.

Fixes #2030.

---

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
• Docs
  • jsdocs: All public APIs documented
  • README: README and/or documentation topic updated
• Title and Description
  • Change type: title prefixed with fix, feat 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)

---

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