Add Database support

[bkolobara]

For the first release (MVP), I would just focus on getting only support for SQLite.

For the distributed part, we can go the fly.io way: https://fly.io/blog/all-in-on-sqlite-litestream/
See also https://tailscale.com/blog/database-for-2022/ & https://blog.cloudflare.com/introducing-d1/

Nice to have features

• Keep SQL in .sql files (similar to Clojure's Yesql and many others with the no-dsl philosophy). This would keep the DX similar to our templating system (compile-time embedding & domain-specific languages stay domain specific).
• Migration tools
• WYSIWYG built in editor for migration creation and looking into the DB content

[MartinKavik]

Perhaps bonsaidb.io would be nice to integrate to have a Rust-only stack including the database, PubSub and a file storage. Just a tip.