Better health check for the external systems

[thangchung]

Something like

public interface IExternalSystem {
  bool Connect();
}

[thangchung]

Upgrading to .NET 2.2:

• https://github.com/xabaril/AspNetCore.Diagnostics.HealthChecks
• https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/health-checks?view=aspnetcore-2.2