fix(phone-sms): 补回 NexSMS provider registry 接入

补回 NexSMS provider adapter，并在 background 与 sidepanel 加载。
同时补充 registry 创建真实 NexSMS provider 的测试，避免后续回归。

sidepanel/sidepanel.html

@@ -1896,6 +1896,7 @@
   <script src="../gopay-utils.js"></script>
   <script src="../phone-sms/providers/hero-sms.js"></script>
   <script src="../phone-sms/providers/five-sim.js"></script>
+  <script src="../phone-sms/providers/nexsms.js"></script>
   <script src="../phone-sms/providers/madao.js"></script>
   <script src="../phone-sms/providers/registry.js"></script>
   <script src="../icloud-utils.js"></script>