Before defining if we will use direct or proxy connection we will exchange a
message with the other peer if the modes match we keep the decision
from the shouldUseProxy function otherwise we skip using direct connection.
Added a feature support message to the signal protocol
* feature: support new management service protocol
* chore: add more logging to track networkmap serial
* refactor: organize peer update code in engine
* chore: fix lint issues
* refactor: extract Signal client interface
* test: add signal client mock
* refactor: introduce Management Service client interface
* chore: place management and signal clients mocks to respective packages
* test: add Serial test to the engine
* fix: lint issues
* test: unit tests for a networkMapUpdate
* test: unit tests Sync update
* fix: too many open files caused by agent not being closed after unsuccessful attempts to start a peer connection (happens when no network available)
* fix: minor refactor to consider signal status
* refactor: move goroutine that runs Signal Client Receive to the engine for better control
* chore: fix comments typo
* test: fix golint
* chore: comments update
* chore: consider connection state=READY in signal and management clients
* chore: fix typos
* test: fix signal ping-pong test
* chore: add wait condition to signal client
* refactor: add stream status to the Signal client
* refactor: defer mutex unlock
