Add code namespace to samples

[bart-vmware]

Most samples don't use a .NET code namespace. The Configuration sample was updated to use the namespace "Steeltoe.Samples.Configuration". This issue tracks the work to use code namespaces across all Steeltoe samples.

Should also adapt the directory and project name, to match up with the namespace. For example, RabbitMQ/RabbitMQ.csproj becomes: Steeltoe.Samples.Connectors.RabbitMQ/Steeltoe.Samples.Connectors.RabbitMQ.csproj