[Cluster] Add Cluster Shared Context

[AntyaDev]

The cluster context should provide functionality:

• [ ] get all nodes info
• [ ] override ScenarioSettings and other parameters in the runtime
• [ ] The API should be integrated into NBomberRunner
• [ ] Share any data between nodes

// Coordinator 
NBomberClusterContext.SetData(string key, object payload);

// Agent
var payload = NBomberClusterContext.GetData(string key);