refactor(ecs): rename hwType in EcsOptimizedAmiProps to `hardware…

[hencrice]

…Type`

This change spells out the previously abbreviated hwType into hardwareType and it closes #2896.

BREAKING CHANGE: the property that specifies the type of EC2 AMI optimized for ECS was renamed to hardwareType from hwType.

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Pull Request Checklist

• [See below] Testing
  • Unit test added (prefer not to modify an existing test, otherwise, it's probably a breaking chaange)
  • [?] CLI change?: coordinate update of integration tests with team
    • scripts/run-integ-parallel @aws-cdk/aws-ecs passed (the command exits with 0). Not sure whether more needs to be done.
  • [?] cdk-init template change?: coordinated update of integration tests with team
    • scripts/run-integ-parallel @aws-cdk/aws-ecs passed (the command exits with 0). Not sure whether more needs to be done.
• 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"
• [N/A] 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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