feat: implement download

Signed-off-by: Sebastian Krupinski <krupinski01@gmail.com>

lib/Client/MessagePart.php

@@ -167,8 +167,9 @@ final class MessagePart
     {
         $data = [
             'partId' => $this->partId,
+            'blobId' => $this->partId,
+            'cId' => $this->contentId,
             'type' => $this->mimeType,
-            'blobId' => $this->contentId,
             'charset' => $this->parameters['charset'] ?? null,
             'name' => $this->parameters['name'] ?? $this->dispositionParameters['filename'] ?? null,
             'encoding' => $this->encoding,