consider package separation

[0xOlias]

it might make sense to move graphql and sqlite to separate packages. these packages could be imported and "plugged in" to the @ponder/core package that contains the core indexing code (and probably also the CLI and dev server?).

this would make it easier to write tests against the indexer.

also, separating out the graphql bits as a plugin would make it easier to allow users to customize the Express server that backs the GraphQL API (add authn, logging, etc).

likewise on the database side. i'm sure many users will prefer to use postgres for GP-like experience.