[Spec][Doc] fury cross-language serialization specification proposal

[chaokunyang]

Is your feature request related to a problem? Please describe.

We've standardized java serialization spec in #1240, but the cross-language serialzation spec has never been formulized.

The current implementation of fury xlang serialization across multiple languages are all based on the code in one of the languages. It's not complete and pone to inconsistencies.

And if some one want to implement Fury for a new language such as Fury C# in #686, he must read all Fury java serialization code. This would be a huge burden for new developers. Not even to say someone may don't write java either.

Another thing is that our xlang serialization is not standardized, we can't have a foundation to discuss how to improve our protocol too.

And our current xlang serialization has many places to improve, such as it didn't resolve the type inconsistencies between languages. Such things should be resolved too.

Describe the solution you'd like

We should design a new protocol for Fury and standardized it as a document.

Additional context

Serialization frameworks such as arrow/avro/hession/thrift/flatbuffer/msgpack all have a serialization spec:

• https://github.com/apache/arrow/blob/main/format/Schema.fbs
• https://numpy.org/doc/stable/user/basics.types.html
• https://thrift.apache.org/docs/types
• https://www.caucho.com/resin-3.1/doc/hessian-2.0-spec.xtp
• https://github.com/msgpack/msgpack/blob/master/spec.md