Use json as input for code generation

[karatakis]

Now we read plain token streams from sea orm generator.

We need to read json produced from sea schema to be more future proof.

Remove sea orm generator dependency and easier to test

[billy1624]

As discussed on Discord. We'll skip the JSON layer and pass seaography_types::SchemaMeta directly into seaography_generator.

The dataflow would be: seaography_discoverer produce SchemaMeta then pass it to seaography_generator for the generation of async-graphql types.

[karatakis]

OUT OF DATE, we depend on sea_orm entities