Fix: Handle unescaped quotes in generate_value using safe_eval

[milk333445]

Description

This PR improves the generate_value function in NeMo-Guardrails/nemoguardrails/actions/llm/generation.py to handle strings with unescaped single and double quotes more robustly. The updated implementation ensures that:

• Strings wrapped in quotes (single or double) are correctly evaluated using literal_eval.
• Strings without quotes are escaped and wrapped in valid Python string syntax before evaluation.
• The function gracefully handles errors caused by invalid input syntax.

Additionally, new test cases have been added NeMo-Guardrails/tests/test_generate_value_safe_eval.py to verify the correctness of safe_eval across different scenarios, including:

• Unquoted strings.
• Strings with nested single and double quotes.
• Empty strings.

All existing and new tests were successfully executed locally using pytest to ensure the changes do not introduce any regressions.

Related Issue(s)

• Fixes bug: Enhance LLM response evaluation in generate_value to handle invalid syntax #938

Checklist

• I've read the CONTRIBUTING guidelines.
• I've updated the documentation if applicable.
• I've added tests if applicable.
• @mentions of the person or team responsible for reviewing proposed changes.

[Pouyanpi]

Thank you @milk333445 for your contribution 👍🏻 Please make the minor changes requested then we are good to merge

[milk333445]

The requested changes have been implemented as follows:

1. Moved the safe_eval function to nemoguardrails/utils.py as suggested.
2. Added logging to capture errors when exceptions are raised.
3. Refactored the test cases:
   • Moved the tests for safe_eval to test_utils.py as it is now part of the utilities.
   • Consolidated all test cases for safe_eval into a single function using pytest.mark.parametrize.

[Pouyanpi]

@milk333445 thanks a lot, it was fast 👍🏻 Just make sure that you sign your commits: you can do an interactive rebase and just sign them, then do a force push.

[milk333445]

I have signed all the commits, and they are now verified.
Please review the changes again and let me know if there's anything else needed. Thank you for your guidance!

[Pouyanpi]

LGTM! 👍🏻