exports: test if a join is already loaded

when a specific join has to be shared between combined filters/aggregators, we need to check if it has been already loaded.
we cannot load it into indicator because result is wrong

src/Bundle/ChillPersonBundle/Export/Aggregator/HouseholdAggregators/ChildrenNumberAggregator.php

@@ -76,6 +76,10 @@ class ChildrenNumberAggregator implements AggregatorInterface
      */
     public function alterQuery(QueryBuilder $qb, $data)
     {
+        if (!in_array('composition', $qb->getAllAliases())) {
+            $qb->join('household.compositions', 'composition');
+        }
+
         $qb->addSelect('composition.numberOfChildren AS childrennumber_aggregator');
 
         $groupBy = $qb->getDQLPart('groupBy');

src/Bundle/ChillPersonBundle/Export/Aggregator/HouseholdAggregators/CompositionAggregator.php

@@ -83,6 +83,10 @@ class CompositionAggregator implements AggregatorInterface
      */
     public function alterQuery(QueryBuilder $qb, $data)
     {
+        if (!in_array('composition', $qb->getAllAliases())) {
+            $qb->join('household.compositions', 'composition');
+        }
+
         $qb->addSelect('IDENTITY(composition.householdCompositionType) AS composition_aggregator');
 
         $groupBy = $qb->getDQLPart('groupBy');

src/Bundle/ChillPersonBundle/Export/Export/CountHousehold.php

@@ -107,7 +107,6 @@ class CountHousehold implements ExportInterface, GroupedExportInterface
             ->join('acppart.person', 'person')
             ->join('person.householdParticipations', 'householdmember')
             ->join('householdmember.household', 'household')
-            ->join('household.compositions', 'composition')
         ;
 
         $qb->select('COUNT(DISTINCT householdmember.household) AS export_result');

src/Bundle/ChillPersonBundle/Export/Filter/HouseholdFilters/CompositionFilter.php

@@ -85,6 +85,10 @@ class CompositionFilter implements FilterInterface
      */
     public function alterQuery(QueryBuilder $qb, $data)
     {
+        if (!in_array('composition', $qb->getAllAliases())) {
+            $qb->join('household.compositions', 'composition');
+        }
+
         $where = $qb->getDQLPart('where');
 
         $clause = $qb->expr()->andX(