Retain Hash when included in URL

[n7studios]

Summary

Fixes this reported issue, where the convertKitRemoveSubscriberIDFromURL method would not include any hash included in the URL.

This bug was introduced in this PR (which introduced using searchParams to fetch URL query parameters, as a more reliable method to detect a ck_subscriber_id and other query parameters, but failed to fetch the URL hash), instead of the previous behaviour of grabbing the entire URL string.

Testing

• SubscriberIDURLCest: Added tests and checks to existing tests to confirm the hash is included when specified, and no hash is appended if not in the URL.

Checklist

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• Code meets WordPress Coding Standards for PHP, HTML, CSS and JS
• Security and Sanitization requirements have been followed
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)