Remove support for ls in multistream-select

[tomaka]

Close #59

[github-actions]

twiggy diff report

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

---

 Delta Bytes │ Item
─────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
        -957 ┊ smoldot::libp2p::connection::multistream_select::MessageOut<I,P>::write_out::h2760269168c2980a
        -957 ┊ smoldot::libp2p::connection::multistream_select::MessageOut<I,P>::write_out::h5a5f075080ae65da
        -957 ┊ smoldot::libp2p::connection::multistream_select::MessageOut<I,P>::write_out::h9c16561c7ea6f1c6
        -458 ┊ <core::iter::adapters::chain::Chain<A,B> as core::iter::traits::iterator::Iterator>::next::h74953e427e82c035
        -427 ┊ smoldot::libp2p::connection::multistream_select::InProgress<I,P>::read_write::hfaca78ebd22a7617
        -427 ┊ smoldot::libp2p::connection::multistream_select::InProgress<I,P>::read_write::hfc2312c93ac27b5c
        -412 ┊ smoldot::libp2p::connection::multistream_select::MessageOut<I,P>::write_out::h17fce128a27686e5
        -412 ┊ smoldot::libp2p::connection::multistream_select::MessageOut<I,P>::write_out::hbf5ecbf21f043a82
        +388 ┊ smoldot::libp2p::connection::multistream_select::MessageOut<P>::write_out::ha2fed198aa9ce7b9
        +388 ┊ smoldot::libp2p::connection::multistream_select::MessageOut<P>::write_out::hb5ea7d9fa803eaf6
        +385 ┊ <core::iter::adapters::chain::Chain<A,B> as core::iter::traits::iterator::Iterator>::next::h0f49a1eb08f38ee7
        -321 ┊ smoldot::libp2p::connection::multistream_select::InProgress<I,P>::read_write::he691383e1e60183f
        -253 ┊ <alloc::vec::Vec<T> as alloc::vec::spec_from_iter_nested::SpecFromIterNested<T,I>>::from_iter::hbaddc0c2824fe30e
        -236 ┊ <alloc::vec::Vec<T> as alloc::vec::spec_from_iter::SpecFromIter<T,alloc::vec::into_iter::IntoIter<T>>>::from_iter::hfb54967c8ea38cf7
        -202 ┊ smoldot::libp2p::connection::multistream_select::MessageOut<I,P>::into_bytes::h78420d4ff19d2f12
        -202 ┊ smoldot::libp2p::connection::multistream_select::MessageOut<I,P>::into_bytes::he88dc0be120efe3e
        -187 ┊ smoldot::libp2p::connection::multistream_select::MessageOut<I,P>::into_bytes::hb4e6908f1a336a08
        +186 ┊ smoldot::libp2p::connection::multistream_select::MessageOut<P>::into_bytes::h2f8c1ed2b3b6290a
        -173 ┊ alloc::raw_vec::RawVec<T,A>::allocate_in::h296d33692cf482df
        -162 ┊ alloc::vec::Vec<T,A>::extend_trusted::h442402238ef56451
       -1375 ┊ ... and 23 more.
       -9841 ┊ Σ [43 Total Rows]