Added Msg91 Adaptor Using Flow

src/Appwrite/Auth/Phone/Msg91Flow.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace Appwrite\Auth\Phone;
+
+use Appwrite\Auth\Phone;
+
+// Reference Material
+// https://docs.msg91.com/p/tf9GTextN/e/Irz7-x1PK/MSG91
+
+class Msg91Flow extends Phone
+{
+    /**
+     * @var string
+     */
+    private string $endpoint = 'https://api.msg91.com/api/v5/flow/';
+
+    /**
+     * For Flow based sending SMS sender ID should not be set in flow
+     * In environment _APP_PHONE_PROVIDER format is 'phone://[senderID]:[authKey]@msg91-flow'.
+     * _APP_PHONE_FROM value is flow ID created in Msg91
+     * Eg. _APP_PHONE_PROVIDER = phone://DINESH:5e1e93cad6fc054d8e759a5b@msg91-flow
+     * _APP_PHONE_FROM = 3968636f704b303135323339
+     * @param string $from-> utilized from for flow id
+     * @param string $to
+     * @param string $message
+     * @return void
+     */
+    public function send(string $from, string $to, string $message): void
+    {
+        $to = ltrim($to, '+');
+        $this->request(
+            method: 'POST',
+            url: $this->endpoint . '/messages',
+            payload: \http_build_query([
+                'sender' => $this->user,
+                'otp' => $message,
+                'flow_id' => $from,
+                'mobiles' => $to
+            ]),
+            headers: [
+                "content-type: application/JSON",
+                "authkey: {$this->secret}",
+            ]
+        );
+    }
+}