v2.0.0

1. Optimized client architecture and project structure, layers become more clear
2. Coversations and messages trigger optimization, better scalability, offline push message title and other fileds become configurable by client
3. Batch insert coversations and messages, the callback triggers faster, and the app initializes messages faster
4. DB field design optimization to increase scalability
5. Add minio interface to upload media file
6. The improvement of the notification messages makes it convenient for the business server to reuse the IM message channel