Decoupled the Console Presentation from the Core Logic into a Service

[MokoSan]

In an effort to separate out the core logic for:

1. Better testability
- Adding functional tests will be easier now that we have removed the Console App based calls from the service.
- Performance testing will also be much easier as it'll be easier to concoct up benchmarking + scenario based perf testing.
2. Better extensibility such as changing the presentation
- Envisioning different presentations can be built on top of the service such as that of a CSV file output or XAML based presentation.
- By encapsulating the GCEnd logic into a simple Observable, we can start building more automated analysis tools (got a # of ideas here and will be happy to discuss via a PR).

We moved the core logic of the GCEnd event into it's own abstraction - the GCRealTimeMonService that's accessed via the IGCRealTimeMonService interface. The contract from the client of the service is to subscribe to the GCEndObservable to obtain the GCEnd events in realtime and call dispose on the IGCRealTimeMonResult once the program is to exit.

Usage:

      IGCRealTimeMonResult result = GCRealTimeMonService.Instance.Value.Initialize(pid: pid, configuration: configuration);
      
      IDisposable subscriptionHandle = result.GCEndObservable.Subscribe(gc =>
      {
          lock (writerLock)
          {
              Console.WriteLine(PrintUtilities.GetRowDetails(gc, configuration));
          }
      });

      result.Source.Process();

When the process needs to exit:

result.Dispose();

[Maoni0]

LGTM - if you could resolve conflicts we can merge :)