Store JSONs are SQLite JSONB

[steida]

One thing I would like to improve is storing JSONs not as strings but as SQLite JSONB. One reason is that right now, Evolu detects stringified JSONs and automatically turns them into objects, which means no user string can be a JSON, which can be confusing. Hence, a Schema String was added to prevent that situation, but I don't like it.

We need the TS version of this: https://github.com/lovasoa/serde-sqlite-jsonb

Inspired by https://github.com/Unconcurrent/SoloDB

We can do the same with a friendly typed API.