Before we extracted the store configuration from the configuration
toml::Value object and passed it to the store.
This is unecessary overhead.
Now we pass the whole configuration object and let the store extract the
required values.
Also change that the implementation uses toml_query::set instead of
toml_query::insert.
Inserting values creates intermediate tables, set doesn't. And we really
want that convenience here, as the code is complex enough on its own.
This merge solved a _LOT_ of conflicts and was a rather complicated one,
as parts of the conflict-resolution involved rewriting of half the
stuff.
This merge commit fixes all the things so a `cargo check --all`
succeeds, but I did not yet check whether tests run without failure.
