bitswap: BitSwapNetwork notifies about connected peers that do not speak Bitswap

[Wondertan]

Here we listen and pass newly connected peers to Bitswap Client and Server. However, we do that for all our peers, including those who do not speak Bitswap protocol.

This is not a big problem because we will quickly realize that such peers are unresponsive, but we could still filter them out much earlier. This potentially warrants migrating to Identify libp2p events that now contain the list of protocols the peer supports.

[lidel]

@Wondertan thank you for filling this, by chance, do you have a ballpark % numbers of usable vs unusable peersyou've experienced?

cc @aschmahmann @gammazero this sounds oddly familiar, could contribute to the bitswap behavior we've seen in Rainbow traces?

[Wondertan]

We don't have any numbers yet. I realized this is an issue while exploring the code for the new protocol we are building over Bitswap. We will be running a single Server over two BitSwapNetwork and I needed to know the implications of that.

[gammazero]

When a peer connects, the peer's supported protocols are not immediately known. We may be able to wait for identify to complete before sending notification, and then see what protos are supported. Any messages from the peer will still cause a connected notification when the state changes to stateResponsive.