Mozilla Referrer-Policy change creates issues on login redirect

Currently after a login, the user is redirected to the original page from which the login procedure was initiated. To this end the DOM `document.referrer` property is used to access the URL of the previous page.

A change in the [Mozilla HTTP referrers policy](https://blog.mozilla.org/security/2021/03/22/firefox-87-trims-http-referrers-by-default-to-protect-user-privacy/) to a privacy related stricter policy changed the default handling of the `document.referrer` property.

With the current GCA-Web code base this now by default leads to an empty `document.referrer` property when using an up to date version of e.g. Firefox. Chrome based browsers still support the redirect method without an issue but this might change in the future.

Check the Mozilla [Referer](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referer) and [RefererPolicy](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy) pages for implementation details.