StepReporter class should be Closable and has a lambda-method

[HardNorth]

Current implementation of StepReporter is way too far from ideal. There is no option to report multi-level steps and it's necessary to finish steps manually each time (inside every agent).

To improve this it is necessary to have a Closable interface implementation, for example:

try(StepReporter.sendStep("Step name")) {
  doSomething();
  doSomethingElse();
}

Another option is to use lambdas:

StepReporter.sendStep("Step name", () -> {
  doSomething();
  StepReporter.sendStep("Inner step name", () -> {
    doSomethingElse();
  });
});

[HardNorth]

A method which returns Closable was reconsidered for implementation, since it's not clear how to handle exceptions inside try-catch blocks.