Add search bar to the Airports list

[DarrianCZE]

When trying to find out whether some airport is present in the database, or what IATA code is used where (we had one discrepancy) there is no option to search the Airport list, and user has to manually click through the list to find what he needs.

[daveroverts]

Won't do this for the moment. I will keep this issue open in case I do plan on adding Filament (#432).

In the meantime, I do accept PR's should you really want to add this in.