feat(codebuild): add support for macOS 15 CodeBuild runners

[ayush-panta]

Reason for this change

Although CodeBuild supports the macOS base:15 image (ref), the CDK does not support this.

Description of changes

I added an option for the BASE_15 image. This simply involved copying the logic for BASE_14 and changing 14 to 15.

Describe any new or updated permissions being added

NA.

Description of how you validated changes

I added unit and integration tests for the base:15 image following the example of the existing tests for the base:14 image.

Unit tests (aws-codebuild/test/project.test.ts) passed locally:

    ✓ has build image for Base 14 (32 ms)
    ✓ has build image for Base 15 (12 ms)
    ✓ can set macOS fleet with BASE_14 (11 ms)
    ✓ can set macOS fleet with BASE_15 (10 ms)
    ✓ can set imported macOS fleet with BASE_14 (11 ms)
    ✓ can set imported macOS fleet with BASE_15 (11 ms)

The integration tests (aws-codebuild/test/integ.project-macos-fleet-base{14/15}.js) were not as straightforward. In the CodeBuild stack logs in my console, the stacks were able to be created successfully but failed to delete. I believe this is expected with macOS fleets and for these test cases, especially as the base:14 test already existed in the codebase. I have included snapshots, as required.

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

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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

[aws-cdk-automation]

(This review is outdated)

✅ Updated pull request passes all PRLinter validations. Dismissing previous PRLinter review.

[ayush-panta]

Though the automated validation passes, I still have to add a snapshot for the base15 integration test.

Update: generated and added.

[ayush-panta]

Hello, just bumping this PR.