Dubbo 3 peripheral RPC protocol and serialization protocol extension implementation

Dubbo 3 needs to support a variety of protocols to facilitate users to implement different situations and need to be implemented based on dubbo-spi-extension.

Project requirements:
- Dubbo 3 supports RMI, thrift, webservice, http and other RPC protocols
- Dubbo 3 supports serialization protocols such as avro, fastjson, fst, gson, kryo, protobuf, protostuff, etc.

Skills requirement:
- Proficiency in Java
- Familiar with Dubbo SPI mechanism
- Understand RPC protocols such as RMI, thrift, webservice, http, etc.
- Understand serialization protocols such as avro, fastjson, fst, gson, kryo, protobuf, protostuff, etc.

Dubbo 3 需要支持多种多样的协议，方便用户落地不同的情况，需要基于 dubbo-spi-extension 实现。

产出要求：
- Dubbo 3 支持 RMI、thrift、webservice、http 等 RPC 协议
- Dubbo 3 支持 avro、fastjson、fst、gson、kryo、protobuf、protostuff 等序列化协议

技术要求：
- 熟练使用 Java
- 熟悉 Dubbo SPI 机制
- 了解 RMI、thrift、webservice、http 等 RPC 协议
- 了解 avro、fastjson、fst、gson、kryo、protobuf、protostuff 等序列化协议