FrontendRedirectSubscriber should protect against being hijacked by 'destination'

Problem/Motivation

Unexpectedly not ending up at the front end.

(
This currently happens with preview routes,
i.e. pressing "Preview" on a node edit screen,
i.e. e.g. https://BACKEND/node/preview/UUID/full?destination=/admin/content.

That will not be an issue anymore when #3320802: Add responsive preview functionality is done / if the responsive_preview module is installed, but I am thinking this is a general source of potential confusion. STR are 'generic'.)

Steps to reproduce

• Try to visit https://BACKEND/node/1?destination=/admin/content
• Expect to end up at https://FRONTEND/node/1?destination=/admin/content
• Instead, end up at https://BACKEND/admin/content

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes