test(storage): refactor unit tests for public & internal facade

[AllanZhengYP]

Description of changes

Refactor the unit test to better reflect the folder structure of storage category APIs. Now Storage package supports 3 facades of APIs via a single implementation. They are

• public client APIs for web & RN
  • Exported via storage package root.
  • Entrypoint in src/providers/s3/apis root
• public server-side APIs
  • Exported via subpath @aws-amplify/storage/server
  • Entrypoint in src/providers/s3/apis/server root
• StorageBrower-only internal APIs
  • Exported via subpath @aws-amplify/storage/internals
  • Entrypoint in src/internals/apis

All the facades above are calling the implementation path src/providers/s3/apis/internal.

This change reflects the unit tests to the implementation folder structure accordingly.

Issue #, if available

Description of how you validated changes

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.