Refactor MockResponse class and update tests

[Mohataseem89]

refactor mock response handling and improve error behavior.

chnages/improvements:

1. made raise_for_status to behave correctly:
   -it prevents silent failures, critical for API-dependent tests
2. added enter / exit to MockResponse:
   -it will make the mock compatible with code using with requests.get(...)
3. made mock_response fixture safer:
   -it ensures missing/invalid parameters fail loudly rather than silently passing
4. added some comments to improve structure/readability

• closes #xxxx (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.
• If I used AI to develop this pull request, I prompted it to follow AGENTS.md.

[mroeschke]

Thanks for the PR, but I think the current layout is OK for now. If you disagree, please open an issue first to discuss why these changes are needed