ScenarioParser: Add stub constructor with the filename parameter
ProtocolController: Add stub implementation of the `IsAnswerExist` and `NextAnswer` methods
ProtocolController: Implement the `IsAnswerExist` and `NextAnswer` methods
VirtualController: Remove delays before request receiving and answer sending
ProtocolHost: Fix bug with the conclusion logic
ProtocolController: Move next answer switch logic to VirtualController class
Implement cycle mode for the virtual controller and virtual host
ProgramOptions: Rename the kLoopMode constant