test(core): Add missing test fixtures

packages/core/e2e/fixtures/e2e-product-import-asset-urls.csv

@@ -0,0 +1,2 @@
+name  ,slug  ,description  ,assets                          ,facets,optionGroups,optionValues,sku     ,price,taxCategory,stockOnHand,trackInventory,variantAssets,variantFacets
+Guitar,guitar,A nice guitar,http://localhost:3456/guitar.jpg,      ,            ,            ,GUIT0001,8999 ,standard   ,25         ,true          ,             ,

packages/core/e2e/import.e2e-spec.ts

@@ -498,7 +498,7 @@ describe('Import resolver', () => {
 
             expect(productResult.products.items.length).toBe(1);
             expect(productResult.products.items[0].featuredAsset.preview).toBe(
-                'test-url/test-assets/guitar__preview.png',
+                'test-url/test-assets/guitar__preview.jpg',
             );
         });
     });