refactor(l1): use threads::Genserver for synchronic threaded code

[lakshya-sky]

** Motivation **
Block execution is sync code and can benefit from using sync version of GenServer that relies on threads.

** Changes **

• use crossbeam channel instead of std::sync::mpsc which allows cloning.
• Introduces TrieUpdateWorker and moves thread spawning inside the GenServer::Init.

Closes #5565

[lakshya-sky]

Waiting for upstream changes to be accepted lambdaclass/spawned#64.

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[lakshya-sky]

Hey @ElFantasma, I've pinned the revision of the spawned for now. Might be better to wait for the create to be released.

[Oppen]

Let's move this as a footnote to the bigger comment. With the changes it looks strange.

[Oppen]

I'm confused, with the new actor shouldn't this be handled by spawned? I thought the goal would be for the worker implementation to only need to worry about the loop body.

[lakshya-sky]

Async tasks Genserver uses spawn_listener but here the sync version doesn't have it implemented https://github.com/lambdaclass/spawned/blob/7af72c4ce40eab8b22d33b3302e9da9229319dc0/concurrency/src/threads/stream.rs#L8C1-L17C2 that's why.
Might be a good idea to implement spawn_listener in the upstream. But the function signature of the spawn_listener relies on Stream and the close one I was able to think is IntoInterator. e.g. fn spawn_listener(handle: .., iter: impl IntoIterator<Item = T::CastMsg>) but I was not sure about that change.

Maybe you and @ElFantasma can share some suggestion to implement spawn_listener.

[lakshya-sky]

Raised a PR lambdaclass/spawned#66 which should allow to write

fn init(
        self,
        handle: &spawned_concurrency::threads::GenServerHandle<Self>,
    ) -> Result<Self, Self::Error> {
        let handle = handle.clone();
        let rx = self
            .trie_upd_rx
            .clone()
            .into_iter()
            .map(|u| Self::CastMsg::TrieUpdates(u));

        spawn_listener(handle, rx);
        Ok(self)
    }