M5 - implement min/max peers for ConnectionManager

[noot]

Task summary

we want to keep our peer count between a certain range at all times, this is specified by a minimum and maximum peer count. the ConnectionManager should handle this:

• when a peer connects, if we are over the max peer count, disconnect from some other peer
• when a peer disconnects, if we are under the min peer count, connect to some new peer (optionally, discover new peers if needed)

Other information and links

see https://github.com/MinaProtocol/mina/blob/9b763f675be3eaddc96dc53c86317065ee481a10/src/app/libp2p_helper/src/codanet.go#L197