Make finding emergency aircraft easier in the table view

[mpentler]

Occasionally I've found it difficult to find an emergency aircraft in the table, having to scroll up and down until I can see the corresponding entry with the red cell background. The table being linked to what is visible in the map view is the main reason for this.

I wondered if adding an option to shove 7500/7600/7700 aircraft to the top of the list would be a good idea. It should probably be a toggle in the settings pane as not everyone will want it. It would also be a good idea to keep it off by default, as suggested on the Discord.

I guess also it would good to consider if the only aircraft that get moved up should be ones in the current map view, or whether it should show aircraft globally, ie outside of the current view.