chore(validator): MAPE and json generation

[sthaha]

This commit fixes MAPE calculation and its tests.
Additionally, the json generation is cleaned and added to gen-report as well.

[github-actions]

🤖 SeineSailor

Here is a concise summary of the pull request changes:

Summary: The chore(validator): MAPE and json generation pull request refactors the validator tool, focusing on MAPE calculation, JSON generation, and report creation.

Key Modifications:

1. MAPE calculation: The mape function now returns the MAPE value multiplied by 100, which may affect applications using this function.
2. JSON generation: The create_json function and its helpers are removed, replaced by write_json_report and asdict for JSON generation.
3. Report creation: The JsonTemplate class is updated, removing file_path, machine_spec, and result parameters, and adding machine_specs and results instead.
4. Custom object handling: The CustomEncoder class is improved to better handle custom objects and datetime objects.

Impact on Codebase:

• Applications using the mape function may need to adjust for the changed return value.
• Functions calling the removed validate_arrays function may be affected.
• The external interface remains unaffected, but internal changes may require adjustments in dependent code.

Suggestions for Improvement:

• Consider adding tests to ensure the mape function's changed return value does not break existing functionality.
• Document the changes to the JsonTemplate class and CustomEncoder to facilitate understanding and adoption.
• Review dependent code for potential issues related to the removed validate_arrays function.