Fix prefix_proof misbehavior

[tomaka]

Fix #2946

The behavior of prefix_proof is currently buggy. When a node isn't found in the proof that the remote sent us, we simply discard it instead of adding it to the list of keys to query at the next iteration.
The consequence is that state_getKeysPaged was wrong most the time.

In order to fix this, I had to reorganize the entire function.

There's still an issue because we're asking for too much data, which leads the remote to shutdown the connection, so queries still occasionally fail. But this other issue is not the fault of the prefix_proof module, and this PR is only about fixing prefix_proof.

[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
─────────────┼────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
        +247 ┊ alloc::vec::Vec<T,A>::extend_desugared::hbaeb7f0c5e25a059
        +202 ┊ smoldot::trie::proof_verify::Children::unfold_append_to_key::h1f7a1fcba0cd8176
        +148 ┊ <either::Either<L,R> as core::iter::traits::iterator::Iterator>::next::h9b6915deff098083
        +125 ┊ <core::iter::adapters::map::Map<I,F> as core::iter::traits::iterator::Iterator>::try_fold::h7b6972ecc80fef6e
        -125 ┊ <core::iter::adapters::map::Map<I,F> as core::iter::traits::iterator::Iterator>::try_fold::hd5db437a6e9ea09a
        -122 ┊ <either::Either<L,R> as core::iter::traits::iterator::Iterator>::next::h10547ac7a0b12bb9
        -100 ┊ smoldot::trie::proof_verify::Children::next_nibbles::h307490ac770c6230
         +95 ┊ <alloc::vec::Vec<T,A> as alloc::vec::spec_extend::SpecExtend<T,I>>::spec_extend::h93f182feb68db6c2
         +91 ┊ alloc::vec::Vec<T,A>::push::hd0340debd00be006
         +90 ┊ <alloc::vec::Vec<T,A> as alloc::vec::spec_extend::SpecExtend<T,alloc::vec::into_iter::IntoIter<T>>>::spec_extend::h08ca0219a99450fa
         +86 ┊ <either::Either<L,R> as core::iter::traits::iterator::Iterator>::size_hint::h85c767ac457ee02f
         +75 ┊ core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &mut F>::call_once::h644e5d895be77e94
         +67 ┊ alloc::raw_vec::RawVec<T,A>::reserve::do_reserve_and_handle::he6686bfda2e6fabe
         -67 ┊ alloc::raw_vec::RawVec<T,A>::reserve_for_push::h040e2a53ee67133e
         +67 ┊ alloc::raw_vec::RawVec<T,A>::reserve_for_push::haaba92c871a53828
         -54 ┊ <alloc::vec::Vec<T,A> as alloc::vec::spec_extend::SpecExtend<&T,core::slice::iter::Iter<T>>>::spec_extend::h740c9e6aa5adf877
         +45 ┊ smoldot::trie::prefix_proof::PrefixScan::resume::h87fbd1a5de5445aa
         +39 ┊ alloc::vec::Vec<T,A>::reserve::hfddd7ed887a1783c
         -30 ┊ core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut::h46f84ead4dd7faa8
         +30 ┊ core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut::hb63d68c229629a97
         +37 ┊ ... and 6 more.
       +2010 ┊ Σ [26 Total Rows]