feat(test): add sign in api test generator

[div5yesh]

• [x] PR title and description conform to Pull Request guidelines.

Issue #, if available:

Description of changes:

• add sign in test case generator and mock responses

How did you test these changes? (Please add a line here how the changes were tested)

• [ ] Added Unit Tests
• [ ] Added Integration Tests

Documentation update required?

• [ ] No
• [ ] Yes (Please include a PR link for the documentation update)

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