WDIO - Spec retry + minor tweaks

[unickq]

This pull request includes updates to the CONTRIBUTING.md file and significant enhancements to the generate-report.ts file to support debugging and improve report generation.

Enhancements to generate-report.ts:

• Implemented the functionality to read and log previous reports, aiding in debugging and maintaining report continuity.
• Refactored the method for generating report file names, ensuring compatibility with different operating systems and avoiding invalid characters.
• Enhanced the handling of test retries and flaky test detection by considering the status of previous reports.
• Added debug logging for successful and failed report writing operations.

Typo correction:

• Fixed a typo in the CONTRIBUTING.md file by correcting "unnasigned" to "unassigned".

Or

• Spec retry support Support retries and flaky property for specFileRetries #20
• Output file will work with any nested structure.
• Debug to print reporter messages