[PHP] Add path without expanded path parameters to callApi

In continuation of #3117 it could be useful to know the path of an
endpoint (without path parameters expanded) in the `callApi` method of
`ApiClient`.

This is for use cases where you would create a derived class from
`ApiClient` for manipulating responses from the server before further
processing (#3117) or add extended logging of the API calls.

modules/swagger-codegen/src/main/resources/php/ApiClient.mustache

@@ -123,11 +123,12 @@ class ApiClient
      * @param array  $postData     parameters to be placed in POST body
      * @param array  $headerParams parameters to be place in request header
      * @param string $responseType expected response type of the endpoint
+     * @param string $endpointPath path to method endpoint before expanding parameters
      *
      * @throws \{{invokerPackage}}\ApiException on a non 2xx response
      * @return mixed
      */
-    public function callApi($resourcePath, $method, $queryParams, $postData, $headerParams, $responseType = null)
+    public function callApi($resourcePath, $method, $queryParams, $postData, $headerParams, $responseType = null, $endpointPath = null)
     {
 
         $headers = array();

modules/swagger-codegen/src/main/resources/php/api.mustache

@@ -266,8 +266,14 @@ use \{{invokerPackage}}\ObjectSerializer;
                 '{{httpMethod}}',
                 $queryParams,
                 $httpBody,
-                $headerParams{{#returnType}},
+                $headerParams,
-                '{{returnType}}'{{/returnType}}
+                {{#returnType}}
+                '{{returnType}}',
+                {{/returnType}}
+                {{^returnType}}
+                null,
+                {{/returnType}}
+                '{{path}}'
             );
 
             {{#returnType}}