fix: allow multiple users to access shared dataset

[gbhavya487-ux]

Summary

• Fix admin user creation response to return the newly created user
• Add a test verifying multiple users can access a shared dataset

Testing

• python -m pytest backend/tests/api/test_dataset.py -v
• 1 passed

[gbhavya487-ux]

This issue has been fixed and the changes have been merged in PR #634. Thanks!

[gbhavya487-ux]

Hi, just following up on this PR. The checks are passing and it’s ready for review. Whenever you have time, could you please take a look? Thank you!