Add support for ns_server scheme and seed poller

In order to support requirements of server components we should add a new connection string scheme of ns_server. When used we will allow only a single seed address in the connection string. This single seed address will then be used for ALL config fetches using a special config poller and ALL connections to this seed will be made over non-SSL (as such this should really only ever be used with localhost but for the purposes of testing we will allow other addresses).

This scheme will also put the SDK into a mode where we will allow the ReconfigureTLS function to be used, once it is added. It will also only enable components that are needed by server components.