Added config and services tests

[Du-z]

Added some more config tests.

The failing tests are setup so that ConfigBuilder.Build() builds from the parent ConfigBuilder.Basic rather than the child ConfigBuilder.UseRpc.

This is ultimately the same way that the Service is built also. Their tests fail for the same reason.

I'm not quite sure what the correct fix for this is.

[ProphetLamb]

I merged the commit that continues the building even if the nightly fails

[ProphetLamb]

The behaviour is actually intended, so that we can have a shared configuration, and multiple branching configurations.
I could change this behaviour, by collecting a list, but I am unsure whether this is desireable. I know that ASP.NET does it that way

[Du-z]

I don't think we want this behavior. The services tests fail to get parts of their configuration built because of this.

Collecting a list sounds like it would give us a lot more flexibility