GitLab

Adds callbacks to manage connections, also removes network receiver methods from public graphsync
interface, and updates libp2p to handle go-libp2p-core refactor

move link tracker out of response manager so it can be used for requests

Creates the Response Manager that processes incoming requests, initiates selector traversal, and
generates responses

Refactor peer manager to handle abstract processes, then use the base class for the peer message
manager and the peer response manager

Create a response manager for a single peer to handle assembling and managing responses for a given
peer