Retain original backoffice location on login after timeout

[AndyButland]

Prerequisites

• I have added steps to test this contribution in the description below

Resolves #19971 and #20050

Description

Looks like this issue has come about after the merge of #19663 to address #16772.

With the above code in place, after a timeout you get redirected to an incorrect URL and end up at the root of the website.

With this update, you'll end up on the backoffice page as expected.

Testing

To replicate the issue you can configure a low timeout value with:

  "Global": {
    "TimeOut": "00:00:30",
  },

Navigate to a page in the backoffice and wait until timed out.

After logging in again you will end up on the home page, and with this update in place you'll be back on the page you were previously on in the backoffice.

I've also verified the following that the original fix was intended to ensure.

• Navigate via a direct link to a page in the backoffice when not logged in, log in, and ensure you are shown the page you have direct linked to.
• Navigate via a direct link to a page in the backoffice when not logged in, log in via an external login provider, and ensure you are shown the page you have direct linked to.

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[leekelleher]

Tested out, works as expected! 🚀