Refactor PeerManager to introduce Connectivity Module

[diegomrsantos]

Issue Addressed

https://github.com/sigp/lighthouse/issues/6860

Proposed Changes

1. Introduction of Connectivity Struct:

   • Added a new Connectivity struct that uses the NetworkGlobalsProvider trait.
   • Encapsulates peer management parameters and methods such as dial_peer, peers_discovered, and maintain_peer_count.

2. NetworkGlobalsProvider Trait:

   • A new trait NetworkGlobalsProvider is introduced. The idea is to create a generic and minimal invasive interface to the current code which other projects are free to decide how to implement.
   • Methods include connected_outbound_only_peers, connected_or_dialing_peers, update_min_ttl, and should_dial.

3. Refactoring PeerManager:

   • PeerManager now includes the Connectivity struct.
   • Methods within PeerManager delegate connectivity-related operations to the Connectivity struct. Removed direct use of discovery_enabled and network global operations from PeerManager.

4. File Changes:

   • connectivity.rs: Added implementation of the Connectivity struct.
   • mod.rs: Updated to include the new Connectivity struct and network_globals_provider.
   • network_behaviour.rs: Updated to use connectivity methods for checking connection limits.
   • network_globals_provider.rs: New file introducing the NetworkGlobalsProvider trait and its implementation for Arc<NetworkGlobals<E>>.

Additional Info

The plan is to continue refactoring PeerManager and introducing new modules.

[CLAassistant]

All committers have signed the CLA.

[jimmygchen]

@diegomrsantos @AgeManning is this PR still required?

[AgeManning]

I'm not sure. I think we may have gone another way inside libp2p, right @diegomrsantos ?