Fixes Smile-SA#1591 Smile-SA#1581 Explicit collection page size

when only fetching aggregations.
Keeps the "Show all" working by distinguishing between NO page size set ("Show all") and a page size of 0.
Also covers someone setting a page size of null for the fun.

src/module-elasticsuite-catalog/Controller/Navigation/Filter/Ajax.php

@@ -116,6 +116,8 @@ private function initLayer()
 
         $this->applyFilters();
 
+        $this->layerResolver->get()->getProductCollection()->setPageSize(0);
+
         return $this;
     }
 

src/module-elasticsuite-catalog/Model/ResourceModel/Product/Fulltext/Collection.php

@@ -219,6 +219,21 @@ public function resetOrder()
         return $this;
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    public function setPageSize($size)
+    {
+        /*
+         * Explicitely setting the page size to false or null is to be treated as having not set any page size.
+         * That is: no pagination, all items are expected.
+         */
+        $size = ($size === null) ? false : $size;
+        $this->_pageSize = $size;
+
+        return $this;
+    }
+
     /**
      * {@inheritDoc}
      */
@@ -532,7 +547,7 @@ private function prepareRequest()
         $searchRequestName = $this->searchRequestName;
 
         // Pagination params.
-        $size = $this->_pageSize ? $this->_pageSize : $this->getSize();
+        $size = ($this->_pageSize !== false) ? $this->_pageSize : $this->getSize();
         $from = $size * (max(1, $this->_curPage) - 1);
 
         // Setup sort orders.

src/module-elasticsuite-catalog/Plugin/Ui/Category/Form/DataProviderPlugin.php

@@ -237,7 +237,7 @@ private function getAttributes($category)
             /** @var \Smile\ElasticsuiteCatalog\Model\ResourceModel\Product\Fulltext\Collection $fulltextCollection */
             $fulltextCollection = $this->fulltextCollectionFactory->create();
             $fulltextCollection->setStoreId($storeId)
-                ->setPageSize(1)
+                ->setPageSize(0)
                 ->addFieldToFilter('category_ids', $this->getCategoryFilterParam($category));
 
             $attributeSetIds = array_keys($fulltextCollection->getFacetedData('attribute_set_id'));