Add a Warning when no suitable input configured for the model

[robertcheramy]

In each model, suitable inputs are specified with cfg, for example in the apc_aos model:

  cfg :ftp do
  end

If ftp is not configured in the configuration of oxidized, oxidized will just return status fail, without an hint that no suitable input were found.

input:
  default: ssh, ftp

Error:

W, [2024-12-16T15:18:13.720208 #36399]  WARN -- : /localhost status fail, retry attempt 1

A warning could be implemented in Node::run.