Epic: Implement STING protocol

[kwek20]

Description

Implement the new messaging protocol as proposed by the Hornet team, and further defined by Gal
See the following RFC: iotaledger/tips#1

We will implement the "Still TrInary Network Gossip" protocol which will allow for faster syncing by
a. Seperating between requests and broadcasts of transactions.
b. Allowing to request specific milestones by index.
c. Sharing between nodes information on the milestones in their databases via Heartbeats
d. Eliminates fragmentation of request messages.

This is epic that will group several issues. Must use Zenhub in order to see dependencies (https://www.zenhub.com/)