refactor: updating region_request.py and tests for the class

[drduhe]

Issue #, if available: n/a

Notes

This PR introduces improvements to the RegionRequest class, focusing on cleaner initialization, enhanced validation, and updated unit tests to ensure robust functionality and maintainability. The PR also deletes the test_api.py file as all the tests that were there have been migrated to the associated ImageRequest and RegionRequest class tests.

Key Changes:

1. Improved Initialization:

   • Refactored the class to use helper methods for setting default values and attributes from input data, ensuring consistent behavior and cleaner code.
   • Simplified the constructor by delegating attribute-setting logic to private methods, making the class easier to extend and maintain.

2. Enhanced Validation Logic:

   • Added checks in the is_valid() method to ensure region_bounds is properly set and not left as the default, improving robustness.
   • Retained validation for shared properties, ensuring consistent checks across different request types.

3. Comprehensive Attribute Documentation:

   • Added reStructuredText-style doc comments for all attributes, providing clear descriptions of each field’s purpose and use. This improves code readability and supports better autogenerated documentation.

4. Updated and Expanded Unit Tests:

   • Created new unit tests to cover additional scenarios, including missing or invalid image_id and region_bounds.
   • Ensured that tests align with the improved unittest structure, making it easier to run, debug, and maintain.
   • Added setup and teardown methods to streamline testing and ensure consistent test environments.

Checklist

Before you submit a pull request, please make sure you have the following:

• Code changes are compact and well-structured to facilitate easy review
• Changes are documented in the README.md and other relevant documentation pages
• PR title and description accurately reflect the changes and are detailed enough for historical tracking
• PR contains tests that cover all new code and the code has been manual tested
• All new dependencies are declared (if any), and no unnecessary libraries are added
• Performance impacts (if any) of the changes are evaluated and documented
• Security implications of the changes (if any) are reviewed and addressed
• I have read the Contributing Guidelines and agree to follow the Code of Conduct

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.