refactor(phishing-controller): enhance URL validation and caching in …

[AugmentedMode]

Explanation

The bulk URL scanning functionality in PhishingController previously didn't leverage the URL scan cache that was already implemented for single URL scanning. This meant that even if a URL had been recently scanned, it would be scanned again when included in a bulk scan request, causing unnecessary API calls and increased response times.

This PR extends the caching functionality to the bulkScanUrls method, allowing it to:

1. Check the cache for each URL before sending API requests
2. Only scan URLs that aren't already in the cache
3. Add newly scanned results to the cache for future use
4. Return a combined response of both cached and newly scanned results

This optimization significantly reduces API calls and improves response times for bulk scan operations, especially when the same URLs are frequently scanned.

References

Related to #5625 (Add URL scan cache functionality)
Extends functionality from #5682 (Add bulk scan functionality)