feat(a11y): implement accessibility mobile audit data processing

[petcud]

Jira:
https://jira.corp.adobe.com/browse/SITES-35669

Description:
The implementation extends the existing desktop-only accessibility audit to support both desktop and mobile viewports, with device-specific issue tracking and proper data aggregation.
Key Changes Made:

1. Content-Scraper Integration: Added concurrency: 10 parameter. This tells content-scraper to process URLs in batches of 10 and audit each URL in both desktop and mobile viewports.
2. Mobile File Processing: Enhanced aggregation logic to handle both desktop and mobile files
   1. File Processing: Separates _mobile.json files from regular .json files and creates mappings between desktop/mobile pairs for the same URL.
   2. Device Tracking: Each violation gets tagged with deviceTypes: ['desktop'], ['mobile'], or ['desktop', 'mobile'] for common issues.
3. Device Diff Logic: Implemented logic to identify mobile-only, desktop-only, and common issues
4. Structure Correction: Fixed JSON format to match the agreed structure

[github-actions]

This PR will trigger a minor release when merged.