Fix aggregations use statements and return values

Author: rogyar

app/code/Magento/Cms/Model/ResourceModel/Block/Grid/Collection.php

@@ -6,7 +6,7 @@
 namespace Magento\Cms\Model\ResourceModel\Block\Grid;
 
 use Magento\Framework\Api\Search\SearchResultInterface;
-use Magento\Framework\Search\AggregationInterface;
+use Magento\Framework\Api\Search\AggregationInterface;
 use Magento\Cms\Model\ResourceModel\Block\Collection as BlockCollection;
 
 /**
@@ -82,6 +82,7 @@ public function getAggregations()
     public function setAggregations($aggregations)
     {
         $this->aggregations = $aggregations;
+        return $this;
     }
 
     /**

app/code/Magento/Cms/Model/ResourceModel/Page/Grid/Collection.php

@@ -83,6 +83,7 @@ public function getAggregations()
     public function setAggregations($aggregations)
     {
         $this->aggregations = $aggregations;
+        return $this;
     }
 
     /**

app/code/Magento/Sales/Model/ResourceModel/Grid/Collection.php

@@ -6,7 +6,7 @@
 namespace Magento\Sales\Model\ResourceModel\Grid;
 
 use Magento\Framework\Api\Search\SearchResultInterface;
-use Magento\Framework\Search\AggregationInterface;
+use Magento\Framework\Api\Search\AggregationInterface;
 use Magento\Framework\Model\ResourceModel\Db\Collection\AbstractCollection;
 
 /**
@@ -78,6 +78,7 @@ public function getAggregations()
     public function setAggregations($aggregations)
     {
         $this->aggregations = $aggregations;
+        return $this;
     }
 
     /**