feat: discover artifacts in nested dir

[achrinza]

fixes https://github.com/loopbackio/loopback-next/discussions/7754

Signed-off-by: Rifa Achrinza [email protected]

Checklist

• [x] DCO (Developer Certificate of Origin) signed in all commits
• [x] npm test passes on your machine
• New tests added or existing tests modified to cover all changes
• [x] Code conforms with the style guide
• API Documentation in code was updated
• Documentation in /docs/site was updated
• Affected artifact templates in packages/cli were updated
• Affected example projects in examples/* were updated

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[achrinza]

Test failures are due to existing test fakes that do not support the necessary APIs. Will need to rewrite them.