fix(prophet): Resolved tail probability for prophet (#4) and added MAPE/RMSE metrics (#6)

[dippatel1994]

Description:

Summary

This PR addresses two key updates to the CImpact library:

• Fixes Bug - Tail Area Probability in Prophet Model Always Returns 100% #4: Corrects the tail area probability calculation in the Prophet model, which previously returned a constant 100%. The updated logic now reflects actual forecast uncertainty.
• Closes Enhancement – Add MAPE and RMSE to Evaluation Metrics #6: Adds Mean Absolute Percentage Error (MAPE) and Root Mean Square Error (RMSE) to the evaluation metrics for more comprehensive model performance analysis.

Changes Made

• Refactored tail probability logic in the Prophet model
• Implemented MAPE and RMSE calculations in the evaluation pipeline.

Dependencies: Dependencies on other outstanding PR's, Issues etc.

PR Checklist:

• Branch has no conflicts with the base branch
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds new functionality)
• Branch naming is correct (feature(or)bug/JIRA-xxx)
• Reviewers are set
• Includes dependency update (requirements.txt updated) ?
• Labels are set (Optional)