Rework how the Person entity determines which device_tracker to use

[Hypfer]

As @frenck suggested, moving the discussion from the PR here and reposting it in the process:

Proposed change

When playing around with the demo instance, I saw that person entities had this map view when opening the more-info dialog

When playing around with my HA instance, they didn't.
This confused me, so I looked at the person implementation.

I'd argue that if the latest tracker is home and there is also a latest gps tracker that is also home, there is no point in not using the gps tracker, as it will provide a superset of the data the other non-gps tracker could provide.

While the state of the entity is the same, the difference is that the person only has latitude/longitude attributes if the source of the location data is a gps tracker.

Without those two, it simply vanishes from the default map view.

You also just get a boring history more-info pop up like this one:

instead of the small map like in the screenshot from the demo instance.

Other approaches to be considered

@edenhaus already suggested a slightly different approach:

Instead of using the GPS coordinates, we could also use the coordinates of the zone, where the non_gps one belongs too
Due the big walls in my house the gps accuracy is bigger than the actual zone, so in my case I would prefer the zone coordinates.
Also using the zone coordinates would be more consistent as with your proposal only coordinates would be available if also the gps device is home. In my opinion we should use the zone coordinates

[dxmnkd316]

Would strongly prefer the GPS coordinates of the zone instead of real GPS coordinates to reduce the number of meaningless attribute changes within recorder. I don't need to know that I "moved" from 45.00001 to 45.00003 in latitude, for example.