Browser navigation does not support going back from entity popup (mobile)

[LinqLover]

Steps to reproduce (on mobile):

1. Open an entity (from a dashboard or from Settings > Devices and services > Entities
2. Choose Device Info from the ellipsis menu
3. Navigate back (using browser button/touch gesture) to Device Info (works)
4. Navigate back again

Expected: see previous dashboard/list of entities again

Actual: HomeAssistant page is closed (or in case of the app: app quits)

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Proposed solution (as an outsider of the project): Append a fragment to the URL when opening the pop-up (at least on mobile) so that navigation remembers the previous page (like history.pushState()). Not sure what behavior is desired on the desktop. But on mobile, the pop-up cannot be seen as such, and the fact that the back arrow at the left top does something different than the browser's back button/touch gesture is pretty confusing.

Originally posted in home-assistant/android#4956