(OFBIZ-11313)

The included controller files resolution was previously delayed when
accessing the configuration properties. The issue is that it imposes
callers to handle exceptions when accessing those
properties. Additionally this has the drawback of detecting inclusion
issues late.

We are now retrieving the included files when instantiating the
controller configuration object. This provides more guarantee on the
integrity of instantiated controllers and relax the error handling
requirements on configuration properties callers.