Refactor HTML validation to use ES modules and improve error reporting

[oyessb]

Copilot generated summary:

This pull request significantly refactors the html-validator.js script to improve maintainability and enhance the output of HTML validation results.

Enhancements to validation output and error reporting:

• Added functions to group validation messages by rule, sort them by frequency, and print concise summaries and detailed samples for both errors and warnings, making it easier to identify common issues.
• Introduced an option to display detailed errors for a specific rule, improving the debugging experience for targeted validation problems.

Code modernization and maintainability improvements:

• Migrated from CommonJS (require) to ES module (import) syntax and refactored the script to use modern JavaScript features, such as async/await and arrow functions.
• Improved error handling and exit code management to ensure proper resource cleanup and more predictable script behavior.

[github-actions]

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud