Store peers in the database

[tomaka]

Close #1768

We currently store the finalized state of the chain in the database as a JSON text.
This PR modifies the format and wraps this finalized state of the chain within another object.
The format of the database now looks like {chain:{...}, nodes:{...}}.

The nodes entry stores the list of nodes that we know are part of the network.

The next time a chain is added with a database, we immediately insert the nodes in the k-buckets.

Because the database format is intentionally not stable, we simply ignore faulty values. This PR breaks the format of the database, but database coming from previous versions will simply be ignored.

[mergify]

Automatically approving tomaka's pull requests. This auto-approval will be removed once more maintainers are active.

[github-actions]

twiggy diff report

Difference in .wasm size before and after this pull request.

---

 Delta Bytes │ Item
─────────────┼────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
      +11628 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h3c9e3fe5bec34ba8
      -11628 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h7cc3404db1d81e03
      +11343 ┊ smoldot_light_base::Client<TChain,TPlat>::add_chain::ha5ea49f04b1655bb
      -11192 ┊ smoldot_light_base::Client<TChain,TPlat>::add_chain::h43673acc6b0cbb22
      -11191 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h10d6380aaa593bd8
      +11191 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::habc8728986e5e22a
      -10668 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h49e8b51d1d5b62df
      +10668 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::hfa07384e11a5330b
      -10628 ┊ smoldot::network::service::ChainNetwork<TNow>::next_event::h52cad4c75926f346
      +10628 ┊ smoldot::network::service::ChainNetwork<TNow>::next_event::h64cea0bc1c48044d
       -9676 ┊ smoldot::libp2p::connection::established::substream::Substream<TNow,TRqUd,TNotifUd>::read_write2::h11b95086c6500fce
       +9676 ┊ smoldot::libp2p::connection::established::substream::Substream<TNow,TRqUd,TNotifUd>::read_write2::h9c658de2666beb0f
       +7880 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h6c8e84cd8dcc087f
       -7880 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h714270646b04ed3d
       -7690 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h30e97cdaf7f01d26
       +7690 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h910fa52bbf338bf6
       +6555 ┊ <&mut serde_json::de::Deserializer<R> as serde::de::Deserializer>::deserialize_map::hd95690d034677067
       -6543 ┊ <&mut serde_json::de::Deserializer<R> as serde::de::Deserializer>::deserialize_map::h068b8d0b2867f794
       +6216 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::hc8176cf4d4cd6be1
       -6216 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::hcfc0ce8c464f3797
      +20320 ┊ ... and 19090 more.
      +35022 ┊ Σ [19110 Total Rows]

[melekes]

are you saying services.sync_service.serialize_chain_information() above obtains the database? maybe you thought to say "If the chain information can't be obtained"?