Feature: [export] allow to check multiple geographical layers in

geographical aggregators

BC: saved exports which activated this layers won't work any more. This
is the query to find them:

```sql
SELECT * FROM chill_main_saved_export
WHERE
    options->'export'->'export'->'aggregators'->'accompanyingcourse_geographicalunitstat_aggregator'->>'enabled' = '1'
```

src/Bundle/ChillPersonBundle/Export/Aggregator/AccompanyingCourseAggregators/GeographicalUnitStatAggregator.php

@@ -98,7 +98,7 @@ final class GeographicalUnitStatAggregator implements AggregatorInterface
             'acp_geog_units'
         );
 
-        $qb->andWhere($qb->expr()->eq('acp_geog_units.layer', ':acp_geog_unit_layer'));
+        $qb->andWhere($qb->expr()->in('acp_geog_units.layer', ':acp_geog_unit_layer'));
 
         $qb->setParameter('acp_geog_unit_layer', $data['level']);
 
@@ -131,6 +131,8 @@ final class GeographicalUnitStatAggregator implements AggregatorInterface
                 'choice_label' => function (GeographicalUnitLayer $item) {
                     return $this->translatableStringHelper->localize($item->getName());
                 },
+                'multiple' => true,
+                'expanded' => true,
             ]);
     }
 

src/Bundle/ChillPersonBundle/Export/Aggregator/PersonAggregators/GeographicalUnitAggregator.php

@@ -103,6 +103,8 @@ class GeographicalUnitAggregator implements AggregatorInterface
                 'choice_label' => function (GeographicalUnitLayer $item) {
                     return $this->translatableStringHelper->localize($item->getName());
                 },
+                'multiple' => true,
+                'expanded' => true,
             ]);
     }