fix(gossipsub): forward to floodsub peers

[turuslan]

Description

messages weren't forwarded to floodsub peers

Notes & open questions

rust-libp2p gossipsub forward_msg sends message to explicit and mesh peers only,
which doesn't include floodsub peers.
go-libp2p-pubsub gossipsub forwards messages to explicit and mesh peers too,
as well as floodsub peers (code)
(call stack: PubSub.handleIncomingRPC, PubSub.pushMsg, PubSub.publishMessage, GossipSubRouter.Publish).

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• A changelog entry has been made in the appropriate crates

[jxs]

Hi, and thanks for this!
Spec wise this makes sense to me, but I think we can make it more optimal, with your added code we are iterating the connected_peers again after getting the ones from the explicit_peers, can we do the opposite instead? I.e iterate over the connected_peers and check if the explicit_peers contains them?

[jxs]

LGTM! Thanks!
Can you update the CHANGELOG.md and Cargo.toml files?