Remove Chain.databaseContent function

[tomaka]

Close #2456

This PR removes the Chain.databaseContent function from the public API. Users are supposed to use the chainHead_unstable_finalizedDatabase JSON-RPC function that was added in #2749 instead.

This is an API breaking change. Since #2778 has been merged and is a breaking change, let's do other breaking changes at the same time.

[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
─────────────┼────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
      -11320 ┊ smoldot_light::Client<TPlat,TChain>::add_chain::h6bae6d598e43e304
      +11316 ┊ smoldot_light::Client<TPlat,TChain>::add_chain::h499ef0e7e64826b1
       +2358 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h7065e28fde98499a
       -2358 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h802cedacb1f6cb59
        -688 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h3fccc462bf05b20d
        +688 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::ha2b79c641ac57c98
        +550 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h1a7756fbbc36eadb
        -550 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::ha019be2e422f677b
        +515 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h821dacf17c6e56db
        -515 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h9a46b4d270db5b6e
        -409 ┊ database_content
        -401 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h1bd1190d0b2c874b
        -392 ┊ core::ptr::drop_in_place<futures_util::future::future::remote_handle::Remote<core::future::from_generator::GenFuture<smoldot_light::Client<smoldot_light_wasm::platform::Platform,alloc::vec::Vec<futures_util::abortable::AbortHandle>>::add_chain<alloc::vec::into_iter::IntoIter<smoldot_light::ChainId>>::{{closure}}>>>::h2da2f02512548873
        +392 ┊ core::ptr::drop_in_place<futures_util::future::future::remote_handle::Remote<core::future::from_generator::GenFuture<smoldot_light::Client<smoldot_light_wasm::platform::Platform>::add_chain<alloc::vec::into_iter::IntoIter<smoldot_light::ChainId>>::{{closure}}>>>::h7b996dfe93307331
        -367 ┊ smoldot_light::Client<TPlat,TChain>::remove_chain::h315004cddbd5eb8f
        -339 ┊ smoldot_light::Client<TPlat,TChain>::database_content::h2c4b35658feac101
        +336 ┊ smoldot_light::Client<TPlat,TChain>::remove_chain::h03458a37b14f606e
        +324 ┊ slab::Slab<T>::insert_at::hf0f727febb657083
        -321 ┊ slab::Slab<T>::insert_at::h54793b016165fc0f
        +304 ┊ <smoldot_light_wasm::cpu_rate_limiter::CpuRateLimiter<T> as core::future::future::Future>::poll::h169759c0a81dfbff
       -2010 ┊ ... and 198 more.
       -6936 ┊ Σ [218 Total Rows]