feat(ec2): mutable? param for imported SecurityGroups fixes #4437

[valzam]

Fixes: #4437

This PR adds a mutable? parameter to the fromSecurityGroupId method on the SecurityGroup construct. This prevents CF from adding redundant rules to existing groups.

When mutable is set to false the implementation of addIngressRule and addEgressRule are overwritten to do nothing.

---

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

[mergify]

Thanks so much for taking the time to contribute to the AWS CDK ❤️

We will shortly assign someone to review this pull request and help get it
merged. In the meantime, please take a minute to make sure you follow this
checklist:

• PR title type(scope): text
  • type: fix, feat, refactor go into CHANGELOG, chore is hidden
  • scope: name of module without aws- or cdk- prefix or postfix (e.g. s3 instead of aws-s3-deployment)
  • text: use all lower-case, do not end with a period, do not include issue refs
• PR Description
  • Rationale: describe rationale of change and approach taken
  • Issues: indicate issues fixed via: fixes #xxx or closes #xxx
  • Breaking?: last paragraph: BREAKING CHANGE: <describe what changed + link for details>
• Testing
  • Unit test added. Prefer to add a new test rather than modify existing tests
  • CLI or init templates change? Re-run/add CLI integration tests
• Documentation
  • README: update module README to describe new features
  • API docs: public APIs must be documented. Copy from official AWS docs when possible
  • Design: for significant features, follow design process

[aws-cdk-automation]

AWS CodeBuild CI Report

• Result: SUCCEEDED
• Build Logs (available for 30 days)

Powered by github-codebuild-logs, available on the AWS Serverless Application Repository

[mergify]

Thank you for contributing! Your pull request is now being automatically merged.

[aws-cdk-automation]

AWS CodeBuild CI Report

• Result: SUCCEEDED
• Build Logs (available for 30 days)

Powered by github-codebuild-logs, available on the AWS Serverless Application Repository