[Host.ServiceLocator] Decommision SlimMessageBus.Host.ServiceLocator plugin

[zarusz]

The package SlimMessageBus.Host.ServiceLocator has little purpose these days:

• The instantiation of SMB is much more complex now than it used to be at the beginning.
• Given we have MsDependencyInjection, Autofac, and Unity there are better alternatives.
• The package usage has been very low.

Because of this, I would like to remove the package from the repository and unlist it on NuGet.org.