Replace RawRabbit.vNext with RawRabbit.DependencyInjection.ServiceCollection

[pardahlman]

The project RawRabbit.vNext was created when .NET Core was still ASP.NET Core and everyone talked about "vNext". It originally contained adapters to logging, extensions to IConfiguration and dependency registration in the service collection. However:

• RawRabbit will use LibLog Use LibLog #245, so no need for logging adapter
• The way configuration is extracted from the IConfiguration has changed, and the only thing that is left is a small extension method that does do anything.

The idea is to move the move the dependency registration code to a new package, perhaps named RawRabbit.DependencyInjection.ServiceCollection. This will align service collection with the other DI frameworks' NuGet packages.