Move setup API into core node bundle, so the implementation can be
changed at runtime. Will utilize to add new developer setup bundle so
SSL certificates are not needed for SolarNode development.
Add new developer implementation of setup API, so for SolarNode
development there is no need to go through the node association process.
Mark SetupService and PKIService as optional, so for local development
can deploy the net.solarnetwork.node.setup.developer bundle instead of
having to go through a local node-association setup process.