Feature: Search for a station also posible using external name

[antidodo]

Is your feature request related to a problem? Please describe.

In communication with Aachen, we got the name of the station as the external name, In the search on admin/realms there is no results, and also in the correct realm, /admin/realms/realm_id/stations the external name doesn't return results.

Describe the solution you'd like

adding the external names to the things that get seachet for matches in /admin/realms/realm_id/stations and searching for a station in admin/realms should also display the realm that contains the station.

Describe alternatives you've considered

Additional context