magento/graphql-ce#741: Add extension point to set custom parameters to Query Context object

Author: naydav

app/code/Magento/CustomerGraphQl/etc/extension_attributes.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<!--
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+-->
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
+    <extension_attributes for="Magento\GraphQl\Model\Query\ContextInterface">
+        <attribute code="customer" type="Magento\Customer\Api\Data\CustomerInterface"/>
+    </extension_attributes>
+</config>