Feature/merge 3 0 develop (#298)

* merging 3.0 into develop

* N°5102 - Allow to send emails (eg. notifications) using GSuite SMTP and OAuth
* migration to iTop 3.1

Co-authored-by: Eric Espie <eric.espie@combodo.com>

lib/guzzlehttp/promises/src/TaskQueue.php

@@ -0,0 +1,67 @@
+<?php
+
+namespace GuzzleHttp\Promise;
+
+/**
+ * A task queue that executes tasks in a FIFO order.
+ *
+ * This task queue class is used to settle promises asynchronously and
+ * maintains a constant stack size. You can use the task queue asynchronously
+ * by calling the `run()` function of the global task queue in an event loop.
+ *
+ *     GuzzleHttp\Promise\Utils::queue()->run();
+ */
+class TaskQueue implements TaskQueueInterface
+{
+    private $enableShutdown = true;
+    private $queue = [];
+
+    public function __construct($withShutdown = true)
+    {
+        if ($withShutdown) {
+            register_shutdown_function(function () {
+                if ($this->enableShutdown) {
+                    // Only run the tasks if an E_ERROR didn't occur.
+                    $err = error_get_last();
+                    if (!$err || ($err['type'] ^ E_ERROR)) {
+                        $this->run();
+                    }
+                }
+            });
+        }
+    }
+
+    public function isEmpty()
+    {
+        return !$this->queue;
+    }
+
+    public function add(callable $task)
+    {
+        $this->queue[] = $task;
+    }
+
+    public function run()
+    {
+        while ($task = array_shift($this->queue)) {
+            /** @var callable $task */
+            $task();
+        }
+    }
+
+    /**
+     * The task queue will be run and exhausted by default when the process
+     * exits IFF the exit is not the result of a PHP E_ERROR error.
+     *
+     * You can disable running the automatic shutdown of the queue by calling
+     * this function. If you disable the task queue shutdown process, then you
+     * MUST either run the task queue (as a result of running your event loop
+     * or manually using the run() method) or wait on each outstanding promise.
+     *
+     * Note: This shutdown will occur before any destructors are triggered.
+     */
+    public function disableShutdown()
+    {
+        $this->enableShutdown = false;
+    }
+}