Get rid of libp2p dependency in sc-authority-discovery

[ndkazu]

Issue

#4859

Description

This PR removes libp2p types in authority-discovery, and replace them with network backend agnostic types from sc-network-types.
The sc-network interface is therefore updated accordingly.

[ndkazu]

@dmitry-markin , @bkchr , @lexnv , I think we're ready for a review.

[ndkazu]

It seems that I cannot add new reviewers myself: I don't see the gear usuallly present on the right side of Reviewers

[bkchr]

You are passing the same type as generic argument?

[ndkazu]

The compiler complains that the type of sc_network_types::rec::Key::new cannot be infered, and so passing the type as the generic fixed the problem.

[dmitry-markin]

This is because of the .into() call, as the compiler does not know what to convert the key.to_vec() into. Just keeping it as key.to_vec() should be enough. Also, the KademliaKey that is needed here is under your control, so you can implement From::<libp2p::kad::RecordKey> for it and use key.into() here instead of sc_network_types::rec::Key::new().

[dmitry-markin]

This is going in the right direction! To completely get rid of libp2p types we must ensure no nested types in sc-authority-discovery are libp2p types. After this is done, no .into() and explicit template arguments should be needed.

[dmitry-markin]

What we want is, actually, to get in authority-discovery types without nested libp2p types. In this case, DhtEvent should be updated to carry substrate-specific types and not wrap libp2p (neither litep2p) types. So, no .into() should be needed in this line.

[dmitry-markin]

You will also need to update self.network.put_value(key, value) to use network backend agnostic types all the way down to NetworkWorker (aka "libp2p network backend") / Litep2pNetworkBackend, where this type will be converted into a specific network backend type.

[ndkazu]

@dmitry-markin , sorry! the into() here was not needed. I made it so that substrate/client/network/src/types.rs does not use libp2p at all anymore. DhtEvent should also be free of any use oflibp2p.
This Leaves us with Litep2pNetworkBackend which is still using libp2p. I am planning to start working on substrate/client/network/src/litep2p/mod.rs and all related files to remove libp2p. I just need you to confirm or correct my understanding of the current status before that 😃

[dmitry-markin]

Sounds good! There should be no need for libp2p kademlia types in substrate/client/network/src/litep2p/mod.rs now when you have kad.rs with network backend agnostic types.

Ideally, we should get rid of all libp2p types in litep2p network backend, but better to do it as a follow-up PR.

[dmitry-markin]

@ndkazu thanks for looking into this issue and sorry for slow reviews on my side.

[ndkazu]

@dmitry-markin , what about litep2p ? keep it or remove/replace it?
I see the following import:
litep2p::protocol::libp2p::bitswap::{ BitswapEvent, BitswapHandle, BlockPresenceType, Config, ResponseType, WantType, };