Optimize building ChainInformation and return runtime

[tomaka]

In order to build the ChainInformation (containing the information about the finalized state of a chain) from a chain spec, we need to compile the runtime of the genesis block.

Before this PR, this is done in a very inefficient way: we build the runtime and use it to obtain the Aura config, then build the runtime again and use it to get the Babe config, then sometimes build the runtime again and use it to get the GrandPa config.

This PR optimizes this by having each step return the runtime that has been built so that it can be passed to the next step.

Furthermore, the entire ChainInformation building process now returns the genesis runtime as well.
This is actually the main reason why I open this PR, as I will need the genesis runtime in order to do #1967.

[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
─────────────┼──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
       -3029 ┊ smoldot::chain::chain_information::aura_config::AuraConfiguration::from_virtual_machine_prototype::h5cb392e5f5f79a38
       +2867 ┊ smoldot::chain::chain_information::aura_config::AuraConfiguration::from_virtual_machine_prototype::hb327dc23b598c253
       +2136 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h373766a27e0b79d2
       -2136 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h3d75758c9566d777
       +1958 ┊ smoldot::chain_spec::ChainSpec::as_chain_information::h19298e64b34a601b
       -1645 ┊ smoldot::chain::chain_information::babe_genesis_config::BabeGenesisConfiguration::from_virtual_machine_prototype::h84ef80daea20c85e
       +1628 ┊ smoldot::chain::chain_information::grandpa_genesis_config::GrandpaGenesisConfiguration::from_virtual_machine_prototype::h944a928c6d69d012
       +1436 ┊ smoldot::chain::chain_information::babe_genesis_config::BabeGenesisConfiguration::from_virtual_machine_prototype::hce7645d8a68276cd
       -1295 ┊ smoldot::chain::chain_information::grandpa_genesis_config::GrandpaGenesisConfiguration::from_genesis_storage::h2be30ddcc2b67909
       -1156 ┊ smoldot::chain_spec::ChainSpec::as_chain_information::hd3c85b8707944aff
       -1132 ┊ smoldot::chain::chain_information::grandpa_genesis_config::GrandpaGenesisConfiguration::from_virtual_machine_prototype::hbb69b60d12bbd907
        -996 ┊ smoldot::chain::chain_information::aura_config::AuraConfiguration::from_storage::h741cb524e44c3b1a
        -968 ┊ smoldot::chain::chain_information::babe_genesis_config::BabeGenesisConfiguration::from_genesis_storage::h8c453d680cae3501
        -932 ┊ <smoldot::chain_spec::FromGenesisStorageError as core::fmt::Display>::fmt::h70e27212f3c4796c
        +802 ┊ <smoldot::chain_spec::FromGenesisStorageError as core::fmt::Display>::fmt::haa5b5239ec333b51
        +711 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h8c6287b321e1c85a
        -711 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::hff23585aec78b956
        -417 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h2c2b3625153d2a15
        +417 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::hc8a58986b2b25a46
        +395 ┊ smoldot::executor::host::HostVmPrototype::new::hacf08e80a7ab2264
        -542 ┊ ... and 72 more.
       -4308 ┊ Σ [92 Total Rows]

[tomaka]

Merging as I need these changes in order to progress with #1967