Backport changes about the light client protocol

[tomaka]

Fix #2975

Backports paritytech/substrate#8046
See also paritytech/substrate#12732

[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
─────────────┼──────────────────────────────────────────────────────────────────────────────────────────────────────
       -2138 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h8e4e65654e5d6353
       +2138 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::hf79ae3017d7beef2
       -1864 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h7b776881750092c4
       +1864 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h85c8c5039dd80cda
       +1844 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h9dbe891c8244c1ce
       -1844 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::he60f4b97c8fcc335
       +1578 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h16cc642049b3c889
       -1578 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h35668af63cd979f8
       +1575 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h04eaa5c0cee933a7
       -1575 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h0d2e14bd1a93331e
       +1575 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h48123caf92987ad8
       -1575 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h958b1ad6277d17fb
       -1562 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h25f2b9d1dd84642f
       +1562 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h8e66e0677efcc8e4
       +1560 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h77582c42f1d9dc2e
       -1560 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::he613e7aa9c35cc3d
       +1554 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h527175eedf2e6dd3
       -1554 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::haf9811e9c1f32a5b
       +1551 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h6c601a386c009b5b
       -1551 ┊ <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::hb20d94577b0f7a61
        +197 ┊ ... and 157 more.
        +225 ┊ Σ [177 Total Rows]