JSON Schema for serialized data packs

[hunterhector]

Is your feature request related to a problem? Please describe. JSON Schema can be used to check whether a data pack serialization is correct, which can help the system to locate problems early and precisely. However, currently, there is no JSON Schema defined in this system.

Describe the solution you'd like Create the JSON Schema for the data packs. It'd be nice if we can create a process to create the schema, here is one proposal:

1. To create a data pack with representative entries stored and serialize that to JSON (this process can be stored for future use)
2. May use a tool to convert the JSON to a schema
3. Edit the resulting schema to generalize it if needed.

Describe alternatives you've considered A clear and concise description of any alternative solutions or features you've considered.

Additional context The JSON Schema may need to be updated after https://github.com/asyml/forte/issues/405.