Add plan-prolongation notification if there was a payment by subscription

At now, if there was payment by subscription, a user will get a notification about successful charging. Instead, we want the user receives information about successful plan prolongation, because it was payment by subscription, not manually.

未指定任何文件、测试或入口点。首先定位 TypeScript GraphQL API 中的订阅支付通知流程，并将其当前的收费消息与所需的计划延长消息进行比较；当订阅支付产生后者通知时即表示完成。

由索引模型根据 Issue 内容生成。