fix: anchor function not updating hostname when Config\App::$allowedHostnames is set

[devunee]

Description
When you have set Config\App::$allowedHostnames the hostname should be set in it if the current URL matches. This is working as expected with with the functions base_url and site_url but NOT working with anchor.

It isn't working as expected because when the anchor function is called with a NULL $altConfig parameter, this parameter is modified to the default Config\App value, then it calls site_url and SiteUri::siteUrl with the default Config\App value instead of NULL which causes the line of code that checks for the host and updates it to be ignored.

The fix is quite simple, the function anchor should keep the parameter $altConfig as NULL and do not modify it to the default Config\App value because this will be done by the SiteUri::siteUrl function.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[mergeable]

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[paulbalandan]

Hey @devunee, can you add some tests to confirm that your fix is working as intended?