fix(storage): nextToken is not surfaced when list result contain only CommonPrefix

[HuiSF]

Description of changes

It is a legit case that ListObjectV2 returns a result that contains only CommonPrefix[] and without a Content, and NextContinuationToken can be returned as well.

The current implementation omits nextToken for this case, and makes listing next page impossible.

Fix: surface the nextToken

Issue #, if available

Description of how you validated changes

• manual test with a sample app
• unit tests

Checklist

• [x] PR description included
• [x] yarn test passes
• [x] Unit Tests are changed or added
• [ ] Relevant documentation is changed or added (and PR referenced)

Checklist for repo maintainers

• [ ] Verify E2E tests for existing workflows are working as expected or add E2E tests for newly added workflows
• [ ] New source file paths included in this PR have been added to CODEOWNERS, if appropriate

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

[ashika112]

Thanks Hui Nice Catch !