Refactor: added ping messages for auto peering and refactored code

plugins/autopeering/protocol/incoming_response_processor.go

plugins/autopeering/protocol/outgoing_ping_processor.go

plugins/autopeering/protocol/peer/constants.go

plugins/autopeering/protocol/peer/peer.go

plugins/autopeering/protocol/ping/constants.go

plugins/autopeering/protocol/ping/errors.go

plugins/autopeering/protocol/ping/ping.go

plugins/autopeering/protocol/plugin.go

plugins/autopeering/protocol/request/constants.go

plugins/autopeering/protocol/request/request.go

plugins/autopeering/protocol/request/send.go

plugins/autopeering/protocol/response/constants.go

plugins/autopeering/protocol/types/constants.go

plugins/autopeering/protocol/types/types.go

plugins/autopeering/saltmanager/errors.go

plugins/autopeering/saltmanager/utils.go

plugins/autopeering/server/tcp/constants.go

plugins/autopeering/server/tcp/events.go

plugins/autopeering/server/tcp/server.go

plugins/autopeering/server/tcp/types.go