Aircraft level Hub definitions (#1363)

* Aircraft level Hub definitions

* Add ability to define a hub for an aircraft apart from its subfleet.

* Update csv import/export capability for hub_id field

* Fix importertest source csv

* Fix source csv for updating too

* Update aircraft_empty_cols.csv

Co-authored-by: Nabeel S <nabeelio@users.noreply.github.com>

resources/views/admin/aircraft/table.blade.php

@@ -3,6 +3,7 @@
   <th>Name</th>
   <th style="text-align: center;">Registration</th>
   <th>Subfleet</th>
+  <th style="text-align: center;">Hub</th>
   <th style="text-align: center;">Location</th>
   <th style="text-align: center;">Hours</th>
   <th style="text-align: center;">Active</th>
@@ -22,6 +23,7 @@
           -
         @endif
       </td>
+      <td style="text-align: center;">{{ $ac->hub_id }}</td>
       <td style="text-align: center;">{{ $ac->airport_id }}</td>
       <td style="text-align: center;">
         @minutestotime($ac->flight_time)