Unique page_id for each URL scanned

[a11ya11y]

When running a scan, each URL is assigned a page_id starting from 1 and increasing by 1 with each new URL scanned. The page_id is also used to create the audit_id.

As a result, when merging results from multiple scans, it is necessary to refactor the page_ids and audit_ids to avoid different URLs having the same page_id or audit_id.

Unique page_ids per scan would address this.

But perhaps there's value in basing the page_id on just the URL itself? This would enable those page_ids to be used as unique identifiers for a URL, and they'd be consistent across scans. While the URLs can be used as unique identifiers, I can see value in using page_ids for this purpose.