network: allow multi-role phonebook entries

[algorandskiy]

Summary

1. Allowed a single phonebook entry to have multiple roles
   • P2P node can advertise both gossip and archival capabilities
   • The existing implementation did not support that but it was not an issue because (2) below
2. Moved DHT operations to meshThread from GetPeers:
   • To have all DHT ops in one place
   • To have GeetPeers be non-network query dependent

Test Plan

Added unit tests for multi roles peers in phonebook and peerstore wrapper.