Fix: handle non-standard and non-JSON error responses without AttributeError

[Vishv07]

Summary

Fixes an AttributeError in storage3 where non-2xx responses that lack message, error, or statusCode keys in their JSON body (or return non-JSON payloads like HTML 502/504 gateway errors) crashed with 'dict' object has no attribute 'text' or uncaught JSONDecodeError.

Changes

• In _async/file_api.py, _async/bucket.py, and _sync counterparts:
  • Catch (KeyError, ValueError) when decoding error response JSON.
  • Access exc.response.text instead of resp.text.
  • Pass exc.response.status_code to StorageApiError.
• Added unit regression tests for missing error keys and non-JSON error responses across test_client.py and test_bucket.py (both async and sync).

Verification

• All 51 unit tests in src/storage pass.
• mypy check passes with 0 issues.
• ruff check and ruff format pass cleanly.