chore: update the internal API to use commands

[thantos]

• Updates all internal commands to be RPC only (not REST) and use the command interface.
• Added concept of namespace to commands. Only _internal and _default are exposed right now.
  • rpc rest paths are _rpc/[namespace]/[command]
  • namespaces will allow for common authorization and separate clients.
• Use the ServiceClient for most of the EventualClient, use as the base layer for the rest of the commands.