DAL: add the bootstrap info into Types.Peer.t and remove it from GS

This MR refactors how the DAL node handles the bootstrap info for easier debugging. Before, the information was stored in the GossipSub automaton's connection data type. However, this prevents knowing if a peer is a bootstrap just by looking at the logs (only the identity was displayed).

With this refactoring, the bootstrap peer flag is removed from Gossipsub and rather attached to the notion of "rich" peer defined in Types.Peer module (made of the peer identity, the IP address+port, and now the bootstrap peer).

In a follow-up MR, we'll do the same for the direct flag, and maybe for trused. The outbound flag, which is more related to a connection rather than a peer will remain in Gossipsub's connection type.