replace separate sqlite dependency with async sqlx-sqlite, adapt usages

[syphar]

I'm starting on some refactoring tasks to make many thing more readable and easier to manage.

rusqlite became annoying to manage because sqlx & rusqlite want to link to different versions of the sqlite library.
The really cool features that rusqlite has are unused by us, and we don't need them in the near future.

Like this we can use the same (sqlx) way of doing things with the archive index.

On top of that this also some methods async, though in case of sqlx-sqlite it doesn't make a real difference because sqlx uses a background thread and then still has to do the syncronous sqlite FFI. And I would say that there is not really a big difference between its own background thread, or tokio's spawn_blocking.

While I was on it I used the sqlx QueryBuilder to batch the INSERT statements when we create the index.

[GuillaumeGomez]

Thanks!