Add specific EntityDescription to describe device tracker entities (#126586)

* Add TrackerEntityDescription to describe tracker entities

* Improve

* Adjust components

* Add ScannerEntityDescription

* Simplify

* Revert

* Set TrackerEntity default source type to SourceType.GPS

* Fix rebase

* Adjust default

* Remove source_type from EntityDescription

* Fix rebase

* Docstring

* Remove BaseTrackerEntityDescription