add possibility for application to get information if IO Controller locally has a diagnosis (e.g. wrong neighbor is detected)

For some functionality (IRT, automatic name assignment) it is required to configure PDEV like information into IO Controller.
If IO Controller detects a fault this is currently not visible to for application.

Two things shall be implemented:

• in case an error is detected a diagnosis alarm shall be generated (just like it would be coming via network from an IO Device)
• ReadRecord for index "DiagnosisData" (0xF80C) shall be supported by IO Controller (just like it would be going through the network)

The internal submodule handles of the IO Controller shall be used for this functionality